/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2009 Marco Costalba
+ Copyright (C) 2008-2010 Marco Costalba, Joona Kiiski, Tord Romstad
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
////
#include <cassert>
+#include <cmath>
#include <cstring>
#include <fstream>
#include <iostream>
#include "tt.h"
#include "ucioption.h"
+using std::cout;
+using std::endl;
////
//// Local definitions
/// Types
- // IterationInfoType stores search results for each iteration
- //
- // Because we use relatively small (dynamic) aspiration window,
- // there happens many fail highs and fail lows in root. And
- // because we don't do researches in those cases, "value" stored
- // here is not necessarily exact. Instead in case of fail high/low
- // we guess what the right value might be and store our guess
- // as a "speculated value" and then move on. Speculated values are
- // used just to calculate aspiration window width, so also if are
- // not exact is not big a problem.
- struct IterationInfoType {
+ // ThreadsManager class is used to handle all the threads related stuff in search,
+ // init, starting, parking and, the most important, launching a slave thread at a
+ // split point are what this class does. All the access to shared thread data is
+ // done through this class, so that we avoid using global variables instead.
- IterationInfoType(Value v = Value(0), Value sv = Value(0))
- : value(v), speculatedValue(sv) {}
+ class ThreadsManager {
+ /* As long as the single ThreadsManager object is defined as a global we don't
+ need to explicitly initialize to zero its data members because variables with
+ static storage duration are automatically set to zero before enter main()
+ */
+ public:
+ void init_threads();
+ void exit_threads();
+
+ int active_threads() const { return ActiveThreads; }
+ void set_active_threads(int newActiveThreads) { ActiveThreads = newActiveThreads; }
+ void incrementNodeCounter(int threadID) { threads[threadID].nodes++; }
+ void incrementBetaCounter(Color us, Depth d, int threadID) { threads[threadID].betaCutOffs[us] += unsigned(d); }
+
+ void resetNodeCounters();
+ void resetBetaCounters();
+ int64_t nodes_searched() const;
+ void get_beta_counters(Color us, int64_t& our, int64_t& their) const;
+ bool available_thread_exists(int master) const;
+ bool thread_is_available(int slave, int master) const;
+ bool thread_should_stop(int threadID) const;
+ void wake_sleeping_threads();
+ void put_threads_to_sleep();
+ void idle_loop(int threadID, SplitPoint* waitSp);
+ bool split(const Position& pos, SearchStack* ss, int ply, Value* alpha, const Value beta, Value* bestValue,
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode);
- Value value, speculatedValue;
- };
+ private:
+ friend void poll(SearchStack ss[], int ply);
+ int ActiveThreads;
+ volatile bool AllThreadsShouldExit, AllThreadsShouldSleep;
+ Thread threads[MAX_THREADS];
+ SplitPoint SplitPointStack[MAX_THREADS][ACTIVE_SPLIT_POINTS_MAX];
- // The BetaCounterType class is used to order moves at ply one.
- // Apart for the first one that has its score, following moves
- // normally have score -VALUE_INFINITE, so are ordered according
- // to the number of beta cutoffs occurred under their subtree during
- // the last iteration. The counters are per thread variables to avoid
- // concurrent accessing under SMP case.
+ Lock MPLock, WaitLock;
- struct BetaCounterType {
+#if !defined(_MSC_VER)
+ pthread_cond_t WaitCond;
+#else
+ HANDLE SitIdleEvent[MAX_THREADS];
+#endif
- BetaCounterType();
- void clear();
- void add(Color us, Depth d, int threadID);
- void read(Color us, int64_t& our, int64_t& their);
};
- // The RootMove class is used for moves at the root at the tree. For each
+ // RootMove struct is used for moves at the root at the tree. For each
// root move, we store a score, a node count, and a PV (really a refutation
// in the case of moves which fail low).
struct RootMove {
- RootMove();
- bool operator<(const RootMove&); // used to sort
+ RootMove() { nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL; }
+
+ // RootMove::operator<() is the comparison function used when
+ // sorting the moves. A move m1 is considered to be better
+ // than a move m2 if it has a higher score, or if the moves
+ // have equal score but m1 has the higher node count.
+ bool operator<(const RootMove& m) const {
+
+ return score != m.score ? score < m.score : theirBeta <= m.theirBeta;
+ }
Move move;
Value score;
- int64_t nodes, cumulativeNodes;
+ int64_t nodes, cumulativeNodes, ourBeta, theirBeta;
Move pv[PLY_MAX_PLUS_2];
- int64_t ourBeta, theirBeta;
};
public:
RootMoveList(Position& pos, Move searchMoves[]);
- inline Move get_move(int moveNum) const;
- inline Value get_move_score(int moveNum) const;
- inline void set_move_score(int moveNum, Value score);
- inline void set_move_nodes(int moveNum, int64_t nodes);
- inline void set_beta_counters(int moveNum, int64_t our, int64_t their);
+
+ int move_count() const { return count; }
+ Move get_move(int moveNum) const { return moves[moveNum].move; }
+ Value get_move_score(int moveNum) const { return moves[moveNum].score; }
+ void set_move_score(int moveNum, Value score) { moves[moveNum].score = score; }
+ Move get_move_pv(int moveNum, int i) const { return moves[moveNum].pv[i]; }
+ int64_t get_move_cumulative_nodes(int moveNum) const { return moves[moveNum].cumulativeNodes; }
+
+ void set_move_nodes(int moveNum, int64_t nodes);
+ void set_beta_counters(int moveNum, int64_t our, int64_t their);
void set_move_pv(int moveNum, const Move pv[]);
- inline Move get_move_pv(int moveNum, int i) const;
- inline int64_t get_move_cumulative_nodes(int moveNum) const;
- inline int move_count() const;
- inline void sort();
+ void sort();
void sort_multipv(int n);
private:
};
- /// Constants
+ /// Adjustments
- // Search depth at iteration 1
- const Depth InitialDepth = OnePly /*+ OnePly/2*/;
+ // Step 6. Razoring
- // Depth limit for selective search
- const Depth SelectiveDepth = 7 * OnePly;
+ // Maximum depth for razoring
+ const Depth RazorDepth = 4 * OnePly;
- // Use internal iterative deepening?
- const bool UseIIDAtPVNodes = true;
- const bool UseIIDAtNonPVNodes = true;
+ // Dynamic razoring margin based on depth
+ inline Value razor_margin(Depth d) { return Value(0x200 + 0x10 * int(d)); }
- // Internal iterative deepening margin. At Non-PV moves, when
- // UseIIDAtNonPVNodes is true, we do an internal iterative deepening
- // search when the static evaluation is at most IIDMargin below beta.
- const Value IIDMargin = Value(0x100);
+ // Step 8. Null move search with verification search
- // Easy move margin. An easy move candidate must be at least this much
- // better than the second best move.
- const Value EasyMoveMargin = Value(0x200);
+ // Null move margin. A null move search will not be done if the static
+ // evaluation of the position is more than NullMoveMargin below beta.
+ const Value NullMoveMargin = Value(0x200);
- // Problem margin. If the score of the first move at iteration N+1 has
- // dropped by more than this since iteration N, the boolean variable
- // "Problem" is set to true, which will make the program spend some extra
- // time looking for a better move.
- const Value ProblemMargin = Value(0x28);
+ // Maximum depth for use of dynamic threat detection when null move fails low
+ const Depth ThreatDepth = 5 * OnePly;
- // No problem margin. If the boolean "Problem" is true, and a new move
- // is found at the root which is less than NoProblemMargin worse than the
- // best move from the previous iteration, Problem is set back to false.
- const Value NoProblemMargin = Value(0x14);
+ // Step 9. Internal iterative deepening
- // Null move margin. A null move search will not be done if the approximate
- // evaluation of the position is more than NullMoveMargin below beta.
- const Value NullMoveMargin = Value(0x300);
+ // Minimum depth for use of internal iterative deepening
+ const Depth IIDDepthAtPVNodes = 5 * OnePly;
+ const Depth IIDDepthAtNonPVNodes = 8 * OnePly;
+
+ // At Non-PV nodes we do an internal iterative deepening search
+ // when the static evaluation is at most IIDMargin below beta.
+ const Value IIDMargin = Value(0x100);
- // Pruning criterions. See the code and comments in ok_to_prune() to
- // understand their precise meaning.
- const bool PruneEscapeMoves = false;
- const bool PruneDefendingMoves = false;
- const bool PruneBlockingMoves = false;
+ // Step 11. Decide the new search depth
- // If the TT move is at least SingleReplyMargin better then the
+ // Extensions. Configurable UCI options
+ // Array index 0 is used at non-PV nodes, index 1 at PV nodes.
+ Depth CheckExtension[2], SingleEvasionExtension[2], PawnPushTo7thExtension[2];
+ Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
+
+ // Minimum depth for use of singular extension
+ const Depth SingularExtensionDepthAtPVNodes = 6 * OnePly;
+ const Depth SingularExtensionDepthAtNonPVNodes = 8 * OnePly;
+
+ // If the TT move is at least SingularExtensionMargin better then the
// remaining ones we will extend it.
- const Value SingleReplyMargin = Value(0x20);
+ const Value SingularExtensionMargin = Value(0x20);
+
+ // Step 12. Futility pruning
- // Margins for futility pruning in the quiescence search, and at frontier
- // and near frontier nodes.
+ // Futility margin for quiescence search
const Value FutilityMarginQS = Value(0x80);
- // Each move futility margin is decreased
- const Value IncrementalFutilityMargin = Value(0x8);
+ // Futility lookup tables (initialized at startup) and their getter functions
+ int32_t FutilityMarginsMatrix[16][64]; // [depth][moveNumber]
+ int FutilityMoveCountArray[32]; // [depth]
- // Razoring
- const Depth RazorDepth = 4*OnePly;
+ inline Value futility_margin(Depth d, int mn) { return Value(d < 7 * OnePly ? FutilityMarginsMatrix[Max(d, 0)][Min(mn, 63)] : 2 * VALUE_INFINITE); }
+ inline int futility_move_count(Depth d) { return d < 16 * OnePly ? FutilityMoveCountArray[d] : 512; }
- // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
- const Value RazorMargins[6] = { Value(0x180), Value(0x300), Value(0x300), Value(0x3C0), Value(0x3C0), Value(0x3C0) };
+ // Step 14. Reduced search
- // Remaining depth: 1 ply 1.5 ply 2 ply 2.5 ply 3 ply 3.5 ply
- const Value RazorApprMargins[6] = { Value(0x520), Value(0x300), Value(0x300), Value(0x300), Value(0x300), Value(0x300) };
+ int ReductionLevel = 2; // 0 = most aggressive reductions, 7 = minimum reductions
+ // Reduction lookup tables (initialized at startup) and their getter functions
+ int8_t PVReductionMatrix[8][64][64]; // [depth][moveNumber]
+ int8_t NonPVReductionMatrix[8][64][64]; // [depth][moveNumber]
- /// Variables initialized by UCI options
+ inline Depth pv_reduction(Depth d, int mn) { return (Depth) PVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; }
+ inline Depth nonpv_reduction(Depth d, int mn) { return (Depth) NonPVReductionMatrix[ReductionLevel][Min(d / 2, 63)][Min(mn, 63)]; }
- // Minimum number of full depth (i.e. non-reduced) moves at PV and non-PV nodes
- int LMRPVMoves, LMRNonPVMoves; // heavy SMP read access for the latter
+ // Common adjustments
- // Depth limit for use of dynamic threat detection
- Depth ThreatDepth; // heavy SMP read access
+ // Search depth at iteration 1
+ const Depth InitialDepth = OnePly;
+
+ // Easy move margin. An easy move candidate must be at least this much
+ // better than the second best move.
+ const Value EasyMoveMargin = Value(0x200);
// Last seconds noise filtering (LSN)
const bool UseLSNFiltering = true;
const Value LSNValue = value_from_centipawns(200);
bool loseOnTime = false;
- // Extensions. Array index 0 is used at non-PV nodes, index 1 at PV nodes.
- // There is heavy SMP read access on these arrays
- Depth CheckExtension[2], SingleReplyExtension[2], PawnPushTo7thExtension[2];
- Depth PassedPawnExtension[2], PawnEndgameExtension[2], MateThreatExtension[2];
- // Iteration counters
+ /// Global variables
+
+ // Iteration counter
int Iteration;
- BetaCounterType BetaCounter; // has per-thread internal data
// Scores and number of times the best move changed for each iteration
- IterationInfoType IterationInfo[PLY_MAX_PLUS_2];
+ Value ValueByIteration[PLY_MAX_PLUS_2];
int BestMoveChangesByIteration[PLY_MAX_PLUS_2];
+ // Search window management
+ int AspirationDelta;
+
// MultiPV mode
int MultiPV;
// Time managment variables
- int SearchStartTime;
- int MaxNodes, MaxDepth;
- int MaxSearchTime, AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
- int RootMoveNumber;
- bool InfiniteSearch;
- bool PonderSearch;
- bool StopOnPonderhit;
- bool AbortSearch; // heavy SMP read access
- bool Quit;
- bool FailHigh;
- bool FailLow;
- bool Problem;
+ int SearchStartTime, MaxNodes, MaxDepth, MaxSearchTime;
+ int AbsoluteMaxSearchTime, ExtraSearchTime, ExactMaxTime;
+ bool UseTimeManagement, InfiniteSearch, PonderSearch, StopOnPonderhit;
+ bool FirstRootMove, AbortSearch, Quit, AspirationFailLow;
// Show current line?
bool ShowCurrentLine;
bool UseLogFile;
std::ofstream LogFile;
- // MP related variables
- int ActiveThreads = 1;
+ // Multi-threads related variables
Depth MinimumSplitDepth;
int MaxThreadsPerSplitPoint;
- Thread Threads[THREAD_MAX];
- Lock MPLock;
- Lock IOLock;
- bool AllThreadsShouldExit = false;
- const int MaxActiveSplitPoints = 8;
- SplitPoint SplitPointStack[THREAD_MAX][MaxActiveSplitPoints];
- bool Idle = true;
+ ThreadsManager TM;
-#if !defined(_MSC_VER)
- pthread_cond_t WaitCond;
- pthread_mutex_t WaitLock;
-#else
- HANDLE SitIdleEvent[THREAD_MAX];
-#endif
-
- // Node counters, used only by thread[0] but try to keep in different
- // cache lines (64 bytes each) from the heavy SMP read accessed variables.
+ // Node counters, used only by thread[0] but try to keep in different cache
+ // lines (64 bytes each) from the heavy multi-thread read accessed variables.
int NodesSincePoll;
int NodesBetweenPolls = 30000;
// History table
History H;
-
- /// Functions
+ /// Local functions
Value id_loop(const Position& pos, Move searchMoves[]);
- Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value alpha, Value beta);
+ Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr);
Value search_pv(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
Value search(Position& pos, SearchStack ss[], Value beta, Depth depth, int ply, bool allowNullmove, int threadID, Move excludedMove = MOVE_NONE);
Value qsearch(Position& pos, SearchStack ss[], Value alpha, Value beta, Depth depth, int ply, int threadID);
bool connected_moves(const Position& pos, Move m1, Move m2);
bool value_is_mate(Value value);
bool move_is_killer(Move m, const SearchStack& ss);
- Depth extension(const Position& pos, Move m, bool pvNode, bool capture, bool check, bool singleReply, bool mateThreat, bool* dangerous);
+ Depth extension(const Position&, Move, bool, bool, bool, bool, bool, bool*);
bool ok_to_do_nullmove(const Position& pos);
bool ok_to_prune(const Position& pos, Move m, Move threat);
bool ok_to_use_TT(const TTEntry* tte, Depth depth, Value beta, int ply);
- void update_history(const Position& pos, Move m, Depth depth, Move movesSearched[], int moveCount);
+ Value refine_eval(const TTEntry* tte, Value defaultEval, int ply);
+ void update_history(const Position& pos, Move move, Depth depth, Move movesSearched[], int moveCount);
void update_killers(Move m, SearchStack& ss);
+ void update_gains(const Position& pos, Move move, Value before, Value after);
- bool fail_high_ply_1();
int current_search_time();
int nps();
- void poll();
+ void poll(SearchStack ss[], int ply);
void ponderhit();
- void print_current_line(SearchStack ss[], int ply, int threadID);
void wait_for_stop_or_ponderhit();
void init_ss_array(SearchStack ss[]);
-
- void idle_loop(int threadID, SplitPoint* waitSp);
- void init_split_point_stack();
- void destroy_split_point_stack();
- bool thread_should_stop(int threadID);
- bool thread_is_available(int slave, int master);
- bool idle_thread_exists(int master);
- bool split(const Position& pos, SearchStack* ss, int ply,
- Value *alpha, Value *beta, Value *bestValue,
- const Value futilityValue, const Value approximateValue,
- Depth depth, int *moves,
- MovePicker *mp, int master, bool pvNode);
- void wake_sleeping_threads();
+ void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value);
#if !defined(_MSC_VER)
void *init_thread(void *threadID);
//// Functions
////
+/// init_threads(), exit_threads() and nodes_searched() are helpers to
+/// give accessibility to some TM methods from outside of current file.
+
+void init_threads() { TM.init_threads(); }
+void exit_threads() { TM.exit_threads(); }
+int64_t nodes_searched() { return TM.nodes_searched(); }
+
-/// perft() is our utility to verify move generation is bug free. All the
-/// legal moves up to given depth are generated and counted and the sum returned.
+/// perft() is our utility to verify move generation is bug free. All the legal
+/// moves up to given depth are generated and counted and the sum returned.
int perft(Position& pos, Depth depth)
{
+ StateInfo st;
Move move;
int sum = 0;
- MovePicker mp = MovePicker(pos, MOVE_NONE, depth, H);
+ MovePicker mp(pos, MOVE_NONE, depth, H);
// If we are at the last ply we don't need to do and undo
// the moves, just to count them.
CheckInfo ci(pos);
while ((move = mp.get_next_move()) != MOVE_NONE)
{
- StateInfo st;
pos.do_move(move, st, ci, pos.move_is_check(move, ci));
sum += perft(pos, depth - OnePly);
pos.undo_move(move);
int time[], int increment[], int movesToGo, int maxDepth,
int maxNodes, int maxTime, Move searchMoves[]) {
- // Look for a book move
- if (!infinite && !ponder && get_option_value_bool("OwnBook"))
+ // Initialize global search variables
+ StopOnPonderhit = AbortSearch = Quit = AspirationFailLow = false;
+ MaxSearchTime = AbsoluteMaxSearchTime = ExtraSearchTime = 0;
+ NodesSincePoll = 0;
+ TM.resetNodeCounters();
+ SearchStartTime = get_system_time();
+ ExactMaxTime = maxTime;
+ MaxDepth = maxDepth;
+ MaxNodes = maxNodes;
+ InfiniteSearch = infinite;
+ PonderSearch = ponder;
+ UseTimeManagement = !ExactMaxTime && !MaxDepth && !MaxNodes && !InfiniteSearch;
+
+ // Look for a book move, only during games, not tests
+ if (UseTimeManagement && get_option_value_bool("OwnBook"))
{
- Move bookMove;
if (get_option_value_string("Book File") != OpeningBook.file_name())
OpeningBook.open(get_option_value_string("Book File"));
- bookMove = OpeningBook.get_move(pos);
+ Move bookMove = OpeningBook.get_move(pos);
if (bookMove != MOVE_NONE)
{
- std::cout << "bestmove " << bookMove << std::endl;
+ if (PonderSearch)
+ wait_for_stop_or_ponderhit();
+
+ cout << "bestmove " << bookMove << endl;
return true;
}
}
- // Initialize global search variables
- Idle = false;
- SearchStartTime = get_system_time();
- for (int i = 0; i < THREAD_MAX; i++)
- {
- Threads[i].nodes = 0ULL;
- Threads[i].failHighPly1 = false;
- }
- NodesSincePoll = 0;
- InfiniteSearch = infinite;
- PonderSearch = ponder;
- StopOnPonderhit = false;
- AbortSearch = false;
- Quit = false;
- FailHigh = false;
- FailLow = false;
- Problem = false;
- ExactMaxTime = maxTime;
-
+ // Reset loseOnTime flag at the beginning of a new game
if (button_was_pressed("New Game"))
- loseOnTime = false; // reset at the beginning of a new game
+ loseOnTime = false;
// Read UCI option values
TT.set_size(get_option_value_int("Hash"));
if (button_was_pressed("Clear Hash"))
TT.clear();
- bool PonderingEnabled = get_option_value_bool("Ponder");
- MultiPV = get_option_value_int("MultiPV");
-
- CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
- CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
-
- SingleReplyExtension[1] = Depth(get_option_value_int("Single Reply Extension (PV nodes)"));
- SingleReplyExtension[0] = Depth(get_option_value_int("Single Reply Extension (non-PV nodes)"));
-
+ CheckExtension[1] = Depth(get_option_value_int("Check Extension (PV nodes)"));
+ CheckExtension[0] = Depth(get_option_value_int("Check Extension (non-PV nodes)"));
+ SingleEvasionExtension[1] = Depth(get_option_value_int("Single Evasion Extension (PV nodes)"));
+ SingleEvasionExtension[0] = Depth(get_option_value_int("Single Evasion Extension (non-PV nodes)"));
PawnPushTo7thExtension[1] = Depth(get_option_value_int("Pawn Push to 7th Extension (PV nodes)"));
PawnPushTo7thExtension[0] = Depth(get_option_value_int("Pawn Push to 7th Extension (non-PV nodes)"));
+ PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
+ PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
+ PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
+ PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
+ MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
+ MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
+
+ MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
+ MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
+ ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
+ MultiPV = get_option_value_int("MultiPV");
+ Chess960 = get_option_value_bool("UCI_Chess960");
+ UseLogFile = get_option_value_bool("Use Search Log");
- PassedPawnExtension[1] = Depth(get_option_value_int("Passed Pawn Extension (PV nodes)"));
- PassedPawnExtension[0] = Depth(get_option_value_int("Passed Pawn Extension (non-PV nodes)"));
-
- PawnEndgameExtension[1] = Depth(get_option_value_int("Pawn Endgame Extension (PV nodes)"));
- PawnEndgameExtension[0] = Depth(get_option_value_int("Pawn Endgame Extension (non-PV nodes)"));
-
- MateThreatExtension[1] = Depth(get_option_value_int("Mate Threat Extension (PV nodes)"));
- MateThreatExtension[0] = Depth(get_option_value_int("Mate Threat Extension (non-PV nodes)"));
-
- LMRPVMoves = get_option_value_int("Full Depth Moves (PV nodes)") + 1;
- LMRNonPVMoves = get_option_value_int("Full Depth Moves (non-PV nodes)") + 1;
- ThreatDepth = get_option_value_int("Threat Depth") * OnePly;
-
- Chess960 = get_option_value_bool("UCI_Chess960");
- ShowCurrentLine = get_option_value_bool("UCI_ShowCurrLine");
- UseLogFile = get_option_value_bool("Use Search Log");
if (UseLogFile)
LogFile.open(get_option_value_string("Search Log Filename").c_str(), std::ios::out | std::ios::app);
- MinimumSplitDepth = get_option_value_int("Minimum Split Depth") * OnePly;
- MaxThreadsPerSplitPoint = get_option_value_int("Maximum Number of Threads per Split Point");
-
read_weights(pos.side_to_move());
// Set the number of active threads
int newActiveThreads = get_option_value_int("Threads");
- if (newActiveThreads != ActiveThreads)
+ if (newActiveThreads != TM.active_threads())
{
- ActiveThreads = newActiveThreads;
- init_eval(ActiveThreads);
+ TM.set_active_threads(newActiveThreads);
+ init_eval(TM.active_threads());
}
// Wake up sleeping threads
- wake_sleeping_threads();
-
- for (int i = 1; i < ActiveThreads; i++)
- assert(thread_is_available(i, 0));
+ TM.wake_sleeping_threads();
// Set thinking time
int myTime = time[side_to_move];
int myIncrement = increment[side_to_move];
-
- if (!movesToGo) // Sudden death time control
+ if (UseTimeManagement)
{
- if (myIncrement)
+ if (!movesToGo) // Sudden death time control
{
- MaxSearchTime = myTime / 30 + myIncrement;
- AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
- } else { // Blitz game without increment
- MaxSearchTime = myTime / 30;
- AbsoluteMaxSearchTime = myTime / 8;
+ if (myIncrement)
+ {
+ MaxSearchTime = myTime / 30 + myIncrement;
+ AbsoluteMaxSearchTime = Max(myTime / 4, myIncrement - 100);
+ }
+ else // Blitz game without increment
+ {
+ MaxSearchTime = myTime / 30;
+ AbsoluteMaxSearchTime = myTime / 8;
+ }
}
- }
- else // (x moves) / (y minutes)
- {
- if (movesToGo == 1)
+ else // (x moves) / (y minutes)
{
- MaxSearchTime = myTime / 2;
- AbsoluteMaxSearchTime =
- (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
- } else {
- MaxSearchTime = myTime / Min(movesToGo, 20);
- AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
+ if (movesToGo == 1)
+ {
+ MaxSearchTime = myTime / 2;
+ AbsoluteMaxSearchTime = (myTime > 3000)? (myTime - 500) : ((myTime * 3) / 4);
+ }
+ else
+ {
+ MaxSearchTime = myTime / Min(movesToGo, 20);
+ AbsoluteMaxSearchTime = Min((4 * myTime) / movesToGo, myTime / 3);
+ }
}
- }
- if (PonderingEnabled)
- {
- MaxSearchTime += MaxSearchTime / 4;
- MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
+ if (get_option_value_bool("Ponder"))
+ {
+ MaxSearchTime += MaxSearchTime / 4;
+ MaxSearchTime = Min(MaxSearchTime, AbsoluteMaxSearchTime);
+ }
}
- // Fixed depth or fixed number of nodes?
- MaxDepth = maxDepth;
- if (MaxDepth)
- InfiniteSearch = true; // HACK
-
- MaxNodes = maxNodes;
+ // Set best NodesBetweenPolls interval to avoid lagging under
+ // heavy time pressure.
if (MaxNodes)
- {
NodesBetweenPolls = Min(MaxNodes, 30000);
- InfiniteSearch = true; // HACK
- }
else if (myTime && myTime < 1000)
NodesBetweenPolls = 1000;
else if (myTime && myTime < 5000)
else
NodesBetweenPolls = 30000;
- // Write information to search log file
+ // Write search information to log file
if (UseLogFile)
- LogFile << "Searching: " << pos.to_fen() << std::endl
+ LogFile << "Searching: " << pos.to_fen() << endl
<< "infinite: " << infinite
<< " ponder: " << ponder
<< " time: " << myTime
<< " increment: " << myIncrement
- << " moves to go: " << movesToGo << std::endl;
+ << " moves to go: " << movesToGo << endl;
-
- // LSN filtering. Used only for developing purpose. Disabled by default.
+ // LSN filtering. Used only for developing purposes, disabled by default
if ( UseLSNFiltering
&& loseOnTime)
{
// Step 2. If after last move we decided to lose on time, do it now!
while (SearchStartTime + myTime + 1000 > get_system_time())
- ; // wait here
+ /* wait here */;
}
// We're ready to start thinking. Call the iterative deepening loop function
Value v = id_loop(pos, searchMoves);
- // LSN filtering. Used only for developing purpose. Disabled by default.
if (UseLSNFiltering)
{
// Step 1. If this is sudden death game and our position is hopeless,
if (UseLogFile)
LogFile.close();
- Idle = true;
+ TM.put_threads_to_sleep();
+
return !Quit;
}
+// init_reduction_tables()
-/// init_threads() is called during startup. It launches all helper threads,
-/// and initializes the split point stack and the global locks and condition
-/// objects.
-
-void init_threads() {
-
- volatile int i;
-
-#if !defined(_MSC_VER)
- pthread_t pthread[1];
-#endif
-
- for (i = 0; i < THREAD_MAX; i++)
- Threads[i].activeSplitPoints = 0;
-
- // Initialize global locks
- lock_init(&MPLock, NULL);
- lock_init(&IOLock, NULL);
-
- init_split_point_stack();
-
-#if !defined(_MSC_VER)
- pthread_mutex_init(&WaitLock, NULL);
- pthread_cond_init(&WaitCond, NULL);
-#else
- for (i = 0; i < THREAD_MAX; i++)
- SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
-#endif
-
- // All threads except the main thread should be initialized to idle state
- for (i = 1; i < THREAD_MAX; i++)
- {
- Threads[i].stop = false;
- Threads[i].workIsWaiting = false;
- Threads[i].idle = true;
- Threads[i].running = false;
- }
+void init_reduction_tables(int8_t pvTable[64][64], int8_t nonPvTable[64][64], int pvInhib, int nonPvInhib)
+{
+ double pvBase = 1.001 - log(3.0) * log(16.0) / pvInhib;
+ double nonPvBase = 1.001 - log(3.0) * log(4.0) / nonPvInhib;
- // Launch the helper threads
- for(i = 1; i < THREAD_MAX; i++)
- {
-#if !defined(_MSC_VER)
- pthread_create(pthread, NULL, init_thread, (void*)(&i));
-#else
- DWORD iID[1];
- CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, iID);
-#endif
+ // Init reduction lookup tables
+ for (int i = 1; i < 64; i++) // i == depth (OnePly = 1)
+ for (int j = 1; j < 64; j++) // j == moveNumber
+ {
+ double pvRed = pvBase + log(double(i)) * log(double(j)) / pvInhib;
+ double nonPVRed = nonPvBase + log(double(i)) * log(double(j)) / nonPvInhib;
- // Wait until the thread has finished launching
- while (!Threads[i].running);
- }
+ pvTable[i][j] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(OnePly)) : 0);
+ nonPvTable[i][j] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(OnePly)) : 0);
+ }
}
+// init_search() is called during startup. It initializes various lookup tables
-/// stop_threads() is called when the program exits. It makes all the
-/// helper threads exit cleanly.
-
-void stop_threads() {
-
- ActiveThreads = THREAD_MAX; // HACK
- Idle = false; // HACK
- wake_sleeping_threads();
- AllThreadsShouldExit = true;
- for (int i = 1; i < THREAD_MAX; i++)
- {
- Threads[i].stop = true;
- while(Threads[i].running);
- }
- destroy_split_point_stack();
-}
-
+void init_search() {
-/// nodes_searched() returns the total number of nodes searched so far in
-/// the current search.
+ for (int i = 0; i < 8; i++)
+ init_reduction_tables(PVReductionMatrix[i], NonPVReductionMatrix[i], 4.0 * pow(1.3, i), 2.0 * pow(1.3, i));
-int64_t nodes_searched() {
+ // Init futility margins array
+ for (int i = 0; i < 16; i++) // i == depth (OnePly = 2)
+ for (int j = 0; j < 64; j++) // j == moveNumber
+ {
+ // FIXME: test using log instead of BSR
+ FutilityMarginsMatrix[i][j] = (i < 2 ? 0 : 112 * bitScanReverse32(i * i / 2)) - 8 * j;
+ }
- int64_t result = 0ULL;
- for (int i = 0; i < ActiveThreads; i++)
- result += Threads[i].nodes;
- return result;
+ // Init futility move count array
+ for (int i = 0; i < 32; i++) // i == depth (OnePly = 2)
+ FutilityMoveCountArray[i] = 3 + (1 << (3 * i / 8));
}
pv[ply] = pv[ply + 1] = MOVE_NONE;
currentMove = threatMove = MOVE_NONE;
reduction = Depth(0);
+ eval = VALUE_NONE;
}
void SearchStack::initKillers() {
namespace {
- // id_loop() is the main iterative deepening loop. It calls root_search
+ // id_loop() is the main iterative deepening loop. It calls root_search
// repeatedly with increasing depth until the allocated thinking time has
// been consumed, the user stops the search, or the maximum search depth is
// reached.
Position p(pos);
SearchStack ss[PLY_MAX_PLUS_2];
+ Move EasyMove = MOVE_NONE;
+ Value value, alpha = -VALUE_INFINITE, beta = VALUE_INFINITE;
- // searchMoves are verified, copied, scored and sorted
+ // Moves to search are verified, copied, scored and sorted
RootMoveList rml(p, searchMoves);
+ // Handle special case of searching on a mate/stale position
if (rml.move_count() == 0)
{
if (PonderSearch)
wait_for_stop_or_ponderhit();
- return pos.is_check()? -VALUE_MATE : VALUE_DRAW;
+ return pos.is_check() ? -VALUE_MATE : VALUE_DRAW;
}
- // Print RootMoveList c'tor startup scoring to the standard output,
- // so that we print information also for iteration 1.
- std::cout << "info depth " << 1 << "\ninfo depth " << 1
- << " score " << value_to_string(rml.get_move_score(0))
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv " << rml.get_move(0) << "\n";
+ // Print RootMoveList startup scoring to the standard output,
+ // so to output information also for iteration 1.
+ cout << "info depth " << 1
+ << "\ninfo depth " << 1
+ << " score " << value_to_string(rml.get_move_score(0))
+ << " time " << current_search_time()
+ << " nodes " << TM.nodes_searched()
+ << " nps " << nps()
+ << " pv " << rml.get_move(0) << "\n";
// Initialize
TT.new_search();
H.clear();
init_ss_array(ss);
- IterationInfo[1] = IterationInfoType(rml.get_move_score(0), rml.get_move_score(0));
+ ValueByIteration[1] = rml.get_move_score(0);
Iteration = 1;
// Is one move significantly better than others after initial scoring ?
- Move EasyMove = MOVE_NONE;
if ( rml.move_count() == 1
|| rml.get_move_score(0) > rml.get_move_score(1) + EasyMoveMargin)
EasyMove = rml.get_move(0);
while (Iteration < PLY_MAX)
{
// Initialize iteration
- rml.sort();
Iteration++;
BestMoveChangesByIteration[Iteration] = 0;
- if (Iteration <= 5)
- ExtraSearchTime = 0;
- std::cout << "info depth " << Iteration << std::endl;
+ cout << "info depth " << Iteration << endl;
- // Calculate dynamic search window based on previous iterations
- Value alpha, beta;
-
- if (MultiPV == 1 && Iteration >= 6 && abs(IterationInfo[Iteration - 1].value) < VALUE_KNOWN_WIN)
+ // Calculate dynamic aspiration window based on previous iterations
+ if (MultiPV == 1 && Iteration >= 6 && abs(ValueByIteration[Iteration - 1]) < VALUE_KNOWN_WIN)
{
- int prevDelta1 = IterationInfo[Iteration - 1].speculatedValue - IterationInfo[Iteration - 2].speculatedValue;
- int prevDelta2 = IterationInfo[Iteration - 2].speculatedValue - IterationInfo[Iteration - 3].speculatedValue;
+ int prevDelta1 = ValueByIteration[Iteration - 1] - ValueByIteration[Iteration - 2];
+ int prevDelta2 = ValueByIteration[Iteration - 2] - ValueByIteration[Iteration - 3];
+
+ AspirationDelta = Max(abs(prevDelta1) + abs(prevDelta2) / 2, 16);
+ AspirationDelta = (AspirationDelta + 7) / 8 * 8; // Round to match grainSize
+
+ alpha = Max(ValueByIteration[Iteration - 1] - AspirationDelta, -VALUE_INFINITE);
+ beta = Min(ValueByIteration[Iteration - 1] + AspirationDelta, VALUE_INFINITE);
+ }
- int delta = Max(2 * abs(prevDelta1) + abs(prevDelta2), ProblemMargin);
+ // Choose optimum reduction level
+ ReductionLevel = 2;
- alpha = Max(IterationInfo[Iteration - 1].value - delta, -VALUE_INFINITE);
- beta = Min(IterationInfo[Iteration - 1].value + delta, VALUE_INFINITE);
+ if (UseTimeManagement)
+ {
+ int level = int(floor(log(float(MaxSearchTime) / current_search_time()) / log(2.0) + 1.0));
+ ReductionLevel = Min(Max(level, 0), 7);
}
else
{
- alpha = - VALUE_INFINITE;
- beta = VALUE_INFINITE;
+ //FIXME
}
- // Search to the current depth
- Value value = root_search(p, ss, rml, alpha, beta);
+ // Search to the current depth, rml is updated and sorted, alpha and beta could change
+ value = root_search(p, ss, rml, &alpha, &beta);
// Write PV to transposition table, in case the relevant entries have
// been overwritten during the search.
break; // Value cannot be trusted. Break out immediately!
//Save info about search result
- Value speculatedValue;
- bool fHigh = false;
- bool fLow = false;
- Value delta = value - IterationInfo[Iteration - 1].value;
-
- if (value >= beta)
- {
- assert(delta > 0);
-
- fHigh = true;
- speculatedValue = value + delta;
- BestMoveChangesByIteration[Iteration] += 2; // Allocate more time
- }
- else if (value <= alpha)
- {
- assert(value == alpha);
- assert(delta < 0);
-
- fLow = true;
- speculatedValue = value + delta;
- BestMoveChangesByIteration[Iteration] += 3; // Allocate more time
- } else
- speculatedValue = value;
-
- speculatedValue = Min(Max(speculatedValue, -VALUE_INFINITE), VALUE_INFINITE);
- IterationInfo[Iteration] = IterationInfoType(value, speculatedValue);
+ ValueByIteration[Iteration] = value;
- // Erase the easy move if it differs from the new best move
+ // Drop the easy move if differs from the new best move
if (ss[0].pv[0] != EasyMove)
EasyMove = MOVE_NONE;
- Problem = false;
-
- if (!InfiniteSearch)
+ if (UseTimeManagement)
{
// Time to stop?
bool stopSearch = false;
- // Stop search early if there is only a single legal move
+ // Stop search early if there is only a single legal move,
+ // we search up to Iteration 6 anyway to get a proper score.
if (Iteration >= 6 && rml.move_count() == 1)
stopSearch = true;
// Stop search early when the last two iterations returned a mate score
if ( Iteration >= 6
- && abs(IterationInfo[Iteration].value) >= abs(VALUE_MATE) - 100
- && abs(IterationInfo[Iteration-1].value) >= abs(VALUE_MATE) - 100)
+ && abs(ValueByIteration[Iteration]) >= abs(VALUE_MATE) - 100
+ && abs(ValueByIteration[Iteration-1]) >= abs(VALUE_MATE) - 100)
stopSearch = true;
- // Stop search early if one move seems to be much better than the rest
- int64_t nodes = nodes_searched();
+ // Stop search early if one move seems to be much better than the others
+ int64_t nodes = TM.nodes_searched();
if ( Iteration >= 8
- && !fLow
- && !fHigh
&& EasyMove == ss[0].pv[0]
&& ( ( rml.get_move_cumulative_nodes(0) > (nodes * 85) / 100
&& current_search_time() > MaxSearchTime / 16)
+ BestMoveChangesByIteration[Iteration-1] * (MaxSearchTime / 3);
// Stop search if most of MaxSearchTime is consumed at the end of the
- // iteration. We probably don't have enough time to search the first
+ // iteration. We probably don't have enough time to search the first
// move at the next iteration anyway.
- if (current_search_time() > ((MaxSearchTime + ExtraSearchTime)*80) / 128)
+ if (current_search_time() > ((MaxSearchTime + ExtraSearchTime) * 80) / 128)
stopSearch = true;
if (stopSearch)
{
- if (!PonderSearch)
- break;
- else
+ if (PonderSearch)
StopOnPonderhit = true;
+ else
+ break;
}
}
break;
}
- rml.sort();
-
- // If we are pondering, we shouldn't print the best move before we
- // are told to do so
- if (PonderSearch)
+ // If we are pondering or in infinite search, we shouldn't print the
+ // best move before we are told to do so.
+ if (!AbortSearch && (PonderSearch || InfiniteSearch))
wait_for_stop_or_ponderhit();
else
// Print final search statistics
- std::cout << "info nodes " << nodes_searched()
- << " nps " << nps()
- << " time " << current_search_time()
- << " hashfull " << TT.full() << std::endl;
+ cout << "info nodes " << TM.nodes_searched()
+ << " nps " << nps()
+ << " time " << current_search_time()
+ << " hashfull " << TT.full() << endl;
// Print the best move and the ponder move to the standard output
if (ss[0].pv[0] == MOVE_NONE)
ss[0].pv[0] = rml.get_move(0);
ss[0].pv[1] = MOVE_NONE;
}
- std::cout << "bestmove " << ss[0].pv[0];
+
+ assert(ss[0].pv[0] != MOVE_NONE);
+
+ cout << "bestmove " << ss[0].pv[0];
+
if (ss[0].pv[1] != MOVE_NONE)
- std::cout << " ponder " << ss[0].pv[1];
+ cout << " ponder " << ss[0].pv[1];
- std::cout << std::endl;
+ cout << endl;
if (UseLogFile)
{
if (dbg_show_hit_rate)
dbg_print_hit_rate(LogFile);
- StateInfo st;
- LogFile << "Nodes: " << nodes_searched() << std::endl
- << "Nodes/second: " << nps() << std::endl
- << "Best move: " << move_to_san(p, ss[0].pv[0]) << std::endl;
+ LogFile << "\nNodes: " << TM.nodes_searched()
+ << "\nNodes/second: " << nps()
+ << "\nBest move: " << move_to_san(p, ss[0].pv[0]);
+ StateInfo st;
p.do_move(ss[0].pv[0], st);
- LogFile << "Ponder move: " << move_to_san(p, ss[0].pv[1])
- << std::endl << std::endl;
+ LogFile << "\nPonder move: "
+ << move_to_san(p, ss[0].pv[1]) // Works also with MOVE_NONE
+ << endl;
}
return rml.get_move_score(0);
}
- // root_search() is the function which searches the root node. It is
+ // root_search() is the function which searches the root node. It is
// similar to search_pv except that it uses a different move ordering
- // scheme (perhaps we should try to use this at internal PV nodes, too?)
- // and prints some information to the standard output.
+ // scheme, prints some information to the standard output and handles
+ // the fail low/high loops.
- Value root_search(Position& pos, SearchStack ss[], RootMoveList &rml, Value alpha, Value beta) {
+ Value root_search(Position& pos, SearchStack ss[], RootMoveList& rml, Value* alphaPtr, Value* betaPtr) {
- Value oldAlpha = alpha;
- Value value;
+ EvalInfo ei;
+ StateInfo st;
CheckInfo ci(pos);
+ int64_t nodes;
+ Move move;
+ Depth depth, ext, newDepth;
+ Value value, alpha, beta;
+ bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
+ int researchCountFH, researchCountFL;
+
+ researchCountFH = researchCountFL = 0;
+ alpha = *alphaPtr;
+ beta = *betaPtr;
+ isCheck = pos.is_check();
+
+ // Step 1. Initialize node and poll (omitted at root, but I can see no good reason for this, FIXME)
+ // Step 2. Check for aborted search (omitted at root, because we do not initialize root node)
+ // Step 3. Mate distance pruning (omitted at root)
+ // Step 4. Transposition table lookup (omitted at root)
- // Loop through all the moves in the root move list
- for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
+ // Step 5. Evaluate the position statically
+ // At root we do this only to get reference value for child nodes
+ if (!isCheck)
+ ss[0].eval = evaluate(pos, ei, 0);
+ else
+ ss[0].eval = VALUE_NONE; // HACK because we do not initialize root node
+
+ // Step 6. Razoring (omitted at root)
+ // Step 7. Static null move pruning (omitted at root)
+ // Step 8. Null move search with verification search (omitted at root)
+ // Step 9. Internal iterative deepening (omitted at root)
+
+ // Step extra. Fail low loop
+ // We start with small aspiration window and in case of fail low, we research
+ // with bigger window until we are not failing low anymore.
+ while (1)
{
- if (alpha >= beta)
+ // Sort the moves before to (re)search
+ rml.sort();
+
+ // Step 10. Loop through all moves in the root move list
+ for (int i = 0; i < rml.move_count() && !AbortSearch; i++)
{
- // We failed high, invalidate and skip next moves, leave node-counters
- // and beta-counters as they are and quickly return, we will try to do
- // a research at the next iteration with a bigger aspiration window.
- rml.set_move_score(i, -VALUE_INFINITE);
- continue;
- }
- int64_t nodes;
- Move move;
- StateInfo st;
- Depth ext, newDepth;
+ // This is used by time management
+ FirstRootMove = (i == 0);
- RootMoveNumber = i + 1;
- FailHigh = false;
+ // Save the current node count before the move is searched
+ nodes = TM.nodes_searched();
- // Remember the node count before the move is searched. The node counts
- // are used to sort the root moves at the next iteration.
- nodes = nodes_searched();
+ // Reset beta cut-off counters
+ TM.resetBetaCounters();
- // Reset beta cut-off counters
- BetaCounter.clear();
+ // Pick the next root move, and print the move and the move number to
+ // the standard output.
+ move = ss[0].currentMove = rml.get_move(i);
- // Pick the next root move, and print the move and the move number to
- // the standard output.
- move = ss[0].currentMove = rml.get_move(i);
- if (current_search_time() >= 1000)
- std::cout << "info currmove " << move
- << " currmovenumber " << i + 1 << std::endl;
+ if (current_search_time() >= 1000)
+ cout << "info currmove " << move
+ << " currmovenumber " << i + 1 << endl;
- // Decide search depth for this move
- bool moveIsCheck = pos.move_is_check(move);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
- bool dangerous;
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- newDepth = (Iteration - 2) * OnePly + ext + InitialDepth;
+ moveIsCheck = pos.move_is_check(move);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- // Make the move, and search it
- pos.do_move(move, st, ci, moveIsCheck);
+ // Step 11. Decide the new search depth
+ depth = (Iteration - 2) * OnePly + InitialDepth;
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
+ newDepth = depth + ext;
- if (i < MultiPV)
- {
- // Aspiration window is disabled in multi-pv case
- if (MultiPV > 1)
- alpha = -VALUE_INFINITE;
-
- value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
- // If the value has dropped a lot compared to the last iteration,
- // set the boolean variable Problem to true. This variable is used
- // for time managment: When Problem is true, we try to complete the
- // current iteration before playing a move.
- Problem = (Iteration >= 2 && value <= IterationInfo[Iteration-1].value - ProblemMargin);
-
- if (Problem && StopOnPonderhit)
- StopOnPonderhit = false;
- }
- else
- {
- if ( newDepth >= 3*OnePly
- && i >= MultiPV + LMRPVMoves
- && !dangerous
- && !captureOrPromotion
- && !move_is_castle(move))
- {
- ss[0].reduction = OnePly;
- value = -search(pos, ss, -alpha, newDepth-OnePly, 1, true, 0);
- } else
- value = alpha + 1; // Just to trigger next condition
+ // Step 12. Futility pruning (omitted at root)
- if (value > alpha)
+ // Step extra. Fail high loop
+ // If move fails high, we research with bigger window until we are not failing
+ // high anymore.
+ value = - VALUE_INFINITE;
+
+ while (1)
{
- value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
- if (value > alpha)
+ // Step 13. Make the move
+ pos.do_move(move, st, ci, moveIsCheck);
+
+ // Step extra. pv search
+ // We do pv search for first moves (i < MultiPV)
+ // and for fail high research (value > alpha)
+ if (i < MultiPV || value > alpha)
{
- // Fail high! Set the boolean variable FailHigh to true, and
- // re-search the move with a big window. The variable FailHigh is
- // used for time managment: We try to avoid aborting the search
- // prematurely during a fail high research.
- FailHigh = true;
+ // Aspiration window is disabled in multi-pv case
+ if (MultiPV > 1)
+ alpha = -VALUE_INFINITE;
+
+ // Full depth PV search, done on first move or after a fail high
value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
}
- }
- }
+ else
+ {
+ // Step 14. Reduced search
+ // if the move fails high will be re-searched at full depth
+ bool doFullDepthSearch = true;
+
+ if ( depth >= 3 * OnePly
+ && !dangerous
+ && !captureOrPromotion
+ && !move_is_castle(move))
+ {
+ ss[0].reduction = pv_reduction(depth, i - MultiPV + 2);
+ if (ss[0].reduction)
+ {
+ // Reduced depth non-pv search using alpha as upperbound
+ value = -search(pos, ss, -alpha, newDepth-ss[0].reduction, 1, true, 0);
+ doFullDepthSearch = (value > alpha);
+ }
+ }
+
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
+ {
+ // Full depth non-pv search using alpha as upperbound
+ ss[0].reduction = Depth(0);
+ value = -search(pos, ss, -alpha, newDepth, 1, true, 0);
+
+ // If we are above alpha then research at same depth but as PV
+ // to get a correct score or eventually a fail high above beta.
+ if (value > alpha)
+ value = -search_pv(pos, ss, -beta, -alpha, newDepth, 1, 0);
+ }
+ }
- pos.undo_move(move);
+ // Step 16. Undo move
+ pos.undo_move(move);
- // Finished searching the move. If AbortSearch is true, the search
- // was aborted because the user interrupted the search or because we
- // ran out of time. In this case, the return value of the search cannot
- // be trusted, and we break out of the loop without updating the best
- // move and/or PV.
- if (AbortSearch)
- break;
+ // Can we exit fail high loop ?
+ if (AbortSearch || value < beta)
+ break;
- // Remember the node count for this move. The node counts are used to
- // sort the root moves at the next iteration.
- rml.set_move_nodes(i, nodes_searched() - nodes);
+ // We are failing high and going to do a research. It's important to update
+ // the score before research in case we run out of time while researching.
+ rml.set_move_score(i, value);
+ update_pv(ss, 0);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
+ rml.set_move_pv(i, ss[0].pv);
+
+ // Print information to the standard output
+ print_pv_info(pos, ss, alpha, beta, value);
+
+ // Prepare for a research after a fail high, each time with a wider window
+ *betaPtr = beta = Min(beta + AspirationDelta * (1 << researchCountFH), VALUE_INFINITE);
+ researchCountFH++;
+
+ } // End of fail high loop
+
+ // Finished searching the move. If AbortSearch is true, the search
+ // was aborted because the user interrupted the search or because we
+ // ran out of time. In this case, the return value of the search cannot
+ // be trusted, and we break out of the loop without updating the best
+ // move and/or PV.
+ if (AbortSearch)
+ break;
+
+ // Remember beta-cutoff and searched nodes counts for this move. The
+ // info is used to sort the root moves for the next iteration.
+ int64_t our, their;
+ TM.get_beta_counters(pos.side_to_move(), our, their);
+ rml.set_beta_counters(i, our, their);
+ rml.set_move_nodes(i, TM.nodes_searched() - nodes);
+
+ assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+ assert(value < beta);
+
+ // Step 17. Check for new best move
+ if (value <= alpha && i >= MultiPV)
+ rml.set_move_score(i, -VALUE_INFINITE);
+ else
+ {
+ // PV move or new best move!
- // Remember the beta-cutoff statistics
- int64_t our, their;
- BetaCounter.read(pos.side_to_move(), our, their);
- rml.set_beta_counters(i, our, their);
+ // Update PV
+ rml.set_move_score(i, value);
+ update_pv(ss, 0);
+ TT.extract_pv(pos, ss[0].pv, PLY_MAX);
+ rml.set_move_pv(i, ss[0].pv);
- assert(value >= -VALUE_INFINITE && value <= VALUE_INFINITE);
+ if (MultiPV == 1)
+ {
+ // We record how often the best move has been changed in each
+ // iteration. This information is used for time managment: When
+ // the best move changes frequently, we allocate some more time.
+ if (i > 0)
+ BestMoveChangesByIteration[Iteration]++;
+
+ // Print information to the standard output
+ print_pv_info(pos, ss, alpha, beta, value);
+
+ // Raise alpha to setup proper non-pv search upper bound
+ if (value > alpha)
+ alpha = value;
+ }
+ else // MultiPV > 1
+ {
+ rml.sort_multipv(i);
+ for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
+ {
+ cout << "info multipv " << j + 1
+ << " score " << value_to_string(rml.get_move_score(j))
+ << " depth " << (j <= i ? Iteration : Iteration - 1)
+ << " time " << current_search_time()
+ << " nodes " << TM.nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (int k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
+ cout << rml.get_move_pv(j, k) << " ";
+
+ cout << endl;
+ }
+ alpha = rml.get_move_score(Min(i, MultiPV - 1));
+ }
+ } // PV move or new best move
- if (value <= alpha && i >= MultiPV)
- rml.set_move_score(i, -VALUE_INFINITE);
- else
- {
- // PV move or new best move!
+ assert(alpha >= *alphaPtr);
- // Update PV
- rml.set_move_score(i, value);
- update_pv(ss, 0);
- TT.extract_pv(pos, ss[0].pv, PLY_MAX);
- rml.set_move_pv(i, ss[0].pv);
+ AspirationFailLow = (alpha == *alphaPtr);
- if (MultiPV == 1)
- {
- // We record how often the best move has been changed in each
- // iteration. This information is used for time managment: When
- // the best move changes frequently, we allocate some more time.
- if (i > 0)
- BestMoveChangesByIteration[Iteration]++;
-
- // Print search information to the standard output
- std::cout << "info depth " << Iteration
- << " score " << value_to_string(value)
- << ((value >= beta)?
- " lowerbound" : ((value <= alpha)? " upperbound" : ""))
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
- std::cout << ss[0].pv[j] << " ";
-
- std::cout << std::endl;
-
- if (UseLogFile)
- LogFile << pretty_pv(pos, current_search_time(), Iteration, nodes_searched(), value,
- ((value >= beta)? VALUE_TYPE_LOWER
- : ((value <= alpha)? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT)),
- ss[0].pv)
- << std::endl;
-
- if (value > alpha)
- alpha = value;
-
- // Reset the global variable Problem to false if the value isn't too
- // far below the final value from the last iteration.
- if (value > IterationInfo[Iteration - 1].value - NoProblemMargin)
- Problem = false;
- }
- else // MultiPV > 1
- {
- rml.sort_multipv(i);
- for (int j = 0; j < Min(MultiPV, rml.move_count()); j++)
- {
- int k;
- std::cout << "info multipv " << j + 1
- << " score " << value_to_string(rml.get_move_score(j))
- << " depth " << ((j <= i)? Iteration : Iteration - 1)
- << " time " << current_search_time()
- << " nodes " << nodes_searched()
- << " nps " << nps()
- << " pv ";
-
- for (k = 0; rml.get_move_pv(j, k) != MOVE_NONE && k < PLY_MAX; k++)
- std::cout << rml.get_move_pv(j, k) << " ";
-
- std::cout << std::endl;
- }
- alpha = rml.get_move_score(Min(i, MultiPV-1));
- }
- } // New best move case
+ if (AspirationFailLow && StopOnPonderhit)
+ StopOnPonderhit = false;
+ }
+
+ // Can we exit fail low loop ?
+ if (AbortSearch || !AspirationFailLow)
+ break;
- assert(alpha >= oldAlpha);
+ // Prepare for a research after a fail low, each time with a wider window
+ *alphaPtr = alpha = Max(alpha - AspirationDelta * (1 << researchCountFL), -VALUE_INFINITE);
+ researchCountFL++;
+
+ } // Fail low loop
+
+ // Sort the moves before to return
+ rml.sort();
- FailLow = (alpha == oldAlpha);
- }
return alpha;
}
assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE);
assert(beta > alpha && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
Move movesSearched[256];
EvalInfo ei;
const TTEntry* tte;
Move ttMove, move;
Depth ext, newDepth;
- Value oldAlpha, value;
- bool isCheck, mateThreat, singleReply, moveIsCheck, captureOrPromotion, dangerous;
+ Value bestValue, value, oldAlpha;
+ bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
+ bool mateThreat = false;
int moveCount = 0;
- Value bestValue = -VALUE_INFINITE;
+ bestValue = value = -VALUE_INFINITE;
if (depth < OnePly)
return qsearch(pos, ss, alpha, beta, Depth(0), ply, threadID);
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
+ // Step 1. Initialize node and poll
+ // Polling can abort search.
init_node(ss, ply, threadID);
- // After init_node() that calls poll()
- if (AbortSearch || thread_should_stop(threadID))
+ // Step 2. Check for aborted search and immediate draw
+ if (AbortSearch || TM.thread_should_stop(threadID))
return Value(0);
- if (pos.is_draw())
+ if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
-
- // Mate distance pruning
+ // Step 3. Mate distance pruning
oldAlpha = alpha;
alpha = Max(value_mated_in(ply), alpha);
beta = Min(value_mate_in(ply+1), beta);
if (alpha >= beta)
return alpha;
- // Transposition table lookup. At PV nodes, we don't use the TT for
- // pruning, but only for move ordering. This is to avoid problems in
- // the following areas:
+ // Step 4. Transposition table lookup
+ // At PV nodes, we don't use the TT for pruning, but only for move ordering.
+ // This is to avoid problems in the following areas:
//
// * Repetition draw detection
// * Fifty move rule detection
// * Searching for a mate
// * Printing of full PV line
- //
tte = TT.retrieve(pos.get_key());
ttMove = (tte ? tte->move() : MOVE_NONE);
- // Go with internal iterative deepening if we don't have a TT move
- if (UseIIDAtPVNodes && ttMove == MOVE_NONE && depth >= 5*OnePly)
+ // Step 5. Evaluate the position statically
+ // At PV nodes we do this only to update gain statistics
+ isCheck = pos.is_check();
+ if (!isCheck)
+ {
+ ss[ply].eval = evaluate(pos, ei, threadID);
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
+ }
+
+ // Step 6. Razoring (is omitted in PV nodes)
+ // Step 7. Static null move pruning (is omitted in PV nodes)
+ // Step 8. Null move search with verification search (is omitted in PV nodes)
+
+ // Step 9. Internal iterative deepening
+ if ( depth >= IIDDepthAtPVNodes
+ && ttMove == MOVE_NONE)
{
search_pv(pos, ss, alpha, beta, depth-2*OnePly, ply, threadID);
ttMove = ss[ply].pv[ply];
tte = TT.retrieve(pos.get_key());
-
- // If tte->move() != MOVE_NONE then it equals ttMove
- assert(!(tte && tte->move()) || tte->move() == ttMove);
}
- // Initialize a MovePicker object for the current position, and prepare
- // to search all moves
- isCheck = pos.is_check();
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+
+ // Initialize a MovePicker object for the current position
mateThreat = pos.has_mate_threat(opposite_color(pos.side_to_move()));
- CheckInfo ci(pos);
MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
+ CheckInfo ci(pos);
- // Loop through all legal moves until no moves remain or a beta cutoff
- // occurs.
while ( alpha < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !thread_should_stop(threadID))
+ && !TM.thread_should_stop(threadID))
{
assert(move_is_ok(move));
- singleReply = (isCheck && mp.number_of_evasions() == 1);
+ singleEvasion = (isCheck && mp.number_of_evasions() == 1);
moveIsCheck = pos.move_is_check(move, ci);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- // Decide the new search depth
- ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+ // Step 11. Decide the new search depth
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
- // We want to extend the TT move if it is much better then remaining ones.
- // To verify this we do a reduced search on all the other moves but the ttMove,
- // if result is lower then TT value minus a margin then we assume ttMove is the
- // only one playable. It is a kind of relaxed single reply extension.
- if ( depth >= 6 * OnePly
+ // Singular extension search. We extend the TT move if its value is much better than
+ // its siblings. To verify this we do a reduced search on all the other moves but the
+ // ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
+ if ( depth >= SingularExtensionDepthAtPVNodes
&& tte
&& move == tte->move()
&& ext < OnePly
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- // If search result is well below the foreseen score of the ttMove then we
- // assume ttMove is the only one realistically playable and we extend it.
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
newDepth = depth - OnePly + ext;
- // Update current move
+ // Update current move (this must be done after singular extension search)
movesSearched[moveCount++] = ss[ply].currentMove = move;
- // Make and search the move
+ // Step 12. Futility pruning (is omitted in PV nodes)
+
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- if (moveCount == 1) // The first move in list is the PV
+ // Step extra. pv search (only in PV nodes)
+ // The first move in list is the expected PV
+ if (moveCount == 1)
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
else
{
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
- if ( depth >= 3*OnePly
- && moveCount >= LMRPVMoves
+ bool doFullDepthSearch = true;
+
+ if ( depth >= 3 * OnePly
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
- ss[ply].reduction = OnePly;
- value = -search(pos, ss, -alpha, newDepth-OnePly, ply+1, true, threadID);
+ ss[ply].reduction = pv_reduction(depth, moveCount);
+ if (ss[ply].reduction)
+ {
+ value = -search(pos, ss, -alpha, newDepth-ss[ply].reduction, ply+1, true, threadID);
+ doFullDepthSearch = (value > alpha);
+ }
}
- else
- value = alpha + 1; // Just to trigger next condition
- if (value > alpha) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -alpha, newDepth, ply+1, true, threadID);
+
+ // Step extra. pv search (only in PV nodes)
if (value > alpha && value < beta)
- {
- // When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
- // time managment: We don't want to stop the search early in
- // such cases, because resolving the fail high at ply 1 could
- // result in a big drop in score at the root.
- if (ply == 1 && RootMoveNumber == 1)
- Threads[threadID].failHighPly1 = true;
-
- // A fail high occurred. Re-search at full window (pv search)
value = -search_pv(pos, ss, -beta, -alpha, newDepth, ply+1, threadID);
- Threads[threadID].failHighPly1 = false;
- }
}
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // New best move?
+ // Step 17. Check for new best move
if (value > bestValue)
{
bestValue = value;
if (value == value_mate_in(ply + 1))
ss[ply].mateKiller = move;
}
- // If we are at ply 1, and we are searching the first root move at
- // ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration.
- if ( ply == 1
- && Iteration >= 2
- && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
- Problem = true;
}
- // Split?
- if ( ActiveThreads > 1
+ // Step 18. Check for split
+ if ( TM.active_threads() > 1
&& bestValue < beta
&& depth >= MinimumSplitDepth
&& Iteration <= 99
- && idle_thread_exists(threadID)
+ && TM.available_thread_exists(threadID)
&& !AbortSearch
- && !thread_should_stop(threadID)
- && split(pos, ss, ply, &alpha, &beta, &bestValue, VALUE_NONE, VALUE_NONE,
- depth, &moveCount, &mp, threadID, true))
+ && !TM.thread_should_stop(threadID)
+ && TM.split(pos, ss, ply, &alpha, beta, &bestValue,
+ depth, mateThreat, &moveCount, &mp, threadID, true))
break;
}
- // All legal moves have been searched. A special case: If there were
+ // Step 19. Check for mate and stalemate
+ // All legal moves have been searched and if there were
// no legal moves, it must be mate or stalemate.
if (moveCount == 0)
return (isCheck ? value_mated_in(ply) : VALUE_DRAW);
+ // Step 20. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (AbortSearch || thread_should_stop(threadID))
+ if (AbortSearch || TM.thread_should_stop(threadID))
return bestValue;
if (bestValue <= oldAlpha)
else if (bestValue >= beta)
{
- BetaCounter.add(pos.side_to_move(), depth, threadID);
+ TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
move = ss[ply].pv[ply];
if (!pos.move_is_capture_or_promotion(move))
{
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
Move movesSearched[256];
EvalInfo ei;
const TTEntry* tte;
Move ttMove, move;
Depth ext, newDepth;
- Value approximateEval, nullValue, value, futilityValue, futilityValueScaled;
- bool isCheck, useFutilityPruning, singleReply, moveIsCheck, captureOrPromotion, dangerous;
+ Value bestValue, refinedValue, nullValue, value, futilityValueScaled;
+ bool isCheck, singleEvasion, moveIsCheck, captureOrPromotion, dangerous;
bool mateThreat = false;
int moveCount = 0;
- Value bestValue = -VALUE_INFINITE;
+ refinedValue = bestValue = value = -VALUE_INFINITE;
if (depth < OnePly)
return qsearch(pos, ss, beta-1, beta, Depth(0), ply, threadID);
- // Initialize, and make an early exit in case of an aborted search,
- // an instant draw, maximum ply reached, etc.
+ // Step 1. Initialize node and poll
+ // Polling can abort search.
init_node(ss, ply, threadID);
- // After init_node() that calls poll()
- if (AbortSearch || thread_should_stop(threadID))
+ // Step 2. Check for aborted search and immediate draw
+ if (AbortSearch || TM.thread_should_stop(threadID))
return Value(0);
- if (pos.is_draw())
+ if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
-
- // Mate distance pruning
+ // Step 3. Mate distance pruning
if (value_mated_in(ply) >= beta)
return beta;
if (value_mate_in(ply + 1) < beta)
return beta - 1;
+ // Step 4. Transposition table lookup
+
// We don't want the score of a partial search to overwrite a previous full search
- // TT value, so we use a different position key in case of an excluded move exsists.
+ // TT value, so we use a different position key in case of an excluded move exists.
Key posKey = excludedMove ? pos.get_exclusion_key() : pos.get_key();
- // Transposition table lookup
tte = TT.retrieve(posKey);
ttMove = (tte ? tte->move() : MOVE_NONE);
return value_from_tt(tte->value(), ply);
}
- approximateEval = quick_evaluate(pos);
+ // Step 5. Evaluate the position statically
isCheck = pos.is_check();
- // Null move search
- if ( allowNullmove
- && depth > OnePly
- && !isCheck
- && !value_is_mate(beta)
- && ok_to_do_nullmove(pos)
- && approximateEval >= beta - NullMoveMargin)
+ if (!isCheck)
{
- ss[ply].currentMove = MOVE_NULL;
+ if (tte && (tte->type() & VALUE_TYPE_EVAL))
+ ss[ply].eval = value_from_tt(tte->value(), ply);
+ else
+ ss[ply].eval = evaluate(pos, ei, threadID);
- pos.do_null_move(st);
+ refinedValue = refine_eval(tte, ss[ply].eval, ply); // Enhance accuracy with TT value if possible
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
+ }
- // Null move dynamic reduction based on depth
- int R = (depth >= 5 * OnePly ? 4 : 3);
+ // Step 6. Razoring
+ if ( !value_is_mate(beta)
+ && !isCheck
+ && depth < RazorDepth
+ && refinedValue < beta - razor_margin(depth)
+ && ss[ply - 1].currentMove != MOVE_NULL
+ && ttMove == MOVE_NONE
+ && !pos.has_pawn_on_7th(pos.side_to_move()))
+ {
+ Value rbeta = beta - razor_margin(depth);
+ Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
+ if (v < rbeta)
+ // Logically we should return (v + razor_margin(depth)), but
+ // surprisingly this did slightly weaker in tests.
+ return v;
+ }
+
+ // Step 7. Static null move pruning
+ // We're betting that the opponent doesn't have a move that will reduce
+ // the score by more than fuility_margin(depth) if we do a null move.
+ if ( !isCheck
+ && allowNullmove
+ && depth < RazorDepth
+ && refinedValue - futility_margin(depth, 0) >= beta)
+ return refinedValue - futility_margin(depth, 0);
+
+ // Step 8. Null move search with verification search
+ // When we jump directly to qsearch() we do a null move only if static value is
+ // at least beta. Otherwise we do a null move if static value is not more than
+ // NullMoveMargin under beta.
+ if ( allowNullmove
+ && depth > OnePly
+ && !isCheck
+ && !value_is_mate(beta)
+ && ok_to_do_nullmove(pos)
+ && refinedValue >= beta - (depth >= 4 * OnePly ? NullMoveMargin : 0))
+ {
+ ss[ply].currentMove = MOVE_NULL;
+
+ pos.do_null_move(st);
+
+ // Null move dynamic reduction based on depth
+ int R = 3 + (depth >= 5 * OnePly ? depth / 8 : 0);
// Null move dynamic reduction based on value
- if (approximateEval - beta > PawnValueMidgame)
+ if (refinedValue - beta > PawnValueMidgame)
R++;
nullValue = -search(pos, ss, -(beta-1), depth-R*OnePly, ply+1, false, threadID);
if (nullValue >= beta)
{
+ // Do not return unproven mate scores
+ if (nullValue >= value_mate_in(PLY_MAX))
+ nullValue = beta;
+
if (depth < 6 * OnePly)
- return beta;
+ return nullValue;
// Do zugzwang verification search
Value v = search(pos, ss, beta, depth-5*OnePly, ply, false, threadID);
if (v >= beta)
- return beta;
+ return nullValue;
} else {
// The null move failed low, which means that we may be faced with
// some kind of threat. If the previous move was reduced, check if
return beta - 1;
}
}
- // Null move search not allowed, try razoring
- else if ( !value_is_mate(beta)
- && depth < RazorDepth
- && approximateEval < beta - RazorApprMargins[int(depth) - 2]
- && ss[ply - 1].currentMove != MOVE_NULL
- && ttMove == MOVE_NONE
- && !pos.has_pawn_on_7th(pos.side_to_move()))
- {
- Value rbeta = beta - RazorMargins[int(depth) - 2];
- Value v = qsearch(pos, ss, rbeta-1, rbeta, Depth(0), ply, threadID);
- if (v < rbeta)
- return v;
- }
- // Go with internal iterative deepening if we don't have a TT move
- if (UseIIDAtNonPVNodes && ttMove == MOVE_NONE && depth >= 8*OnePly &&
- !isCheck && evaluate(pos, ei, threadID) >= beta - IIDMargin)
+ // Step 9. Internal iterative deepening
+ if ( depth >= IIDDepthAtNonPVNodes
+ && ttMove == MOVE_NONE
+ && !isCheck
+ && ss[ply].eval >= beta - IIDMargin)
{
- search(pos, ss, beta, Min(depth/2, depth-2*OnePly), ply, false, threadID);
+ search(pos, ss, beta, depth/2, ply, false, threadID);
ttMove = ss[ply].pv[ply];
- tte = TT.retrieve(pos.get_key());
+ tte = TT.retrieve(posKey);
}
- // Initialize a MovePicker object for the current position, and prepare
- // to search all moves.
- MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply]);
- CheckInfo ci(pos);
- futilityValue = VALUE_NONE;
- useFutilityPruning = depth < SelectiveDepth && !isCheck;
-
- // Calculate depth dependant futility pruning parameters
- const int FutilityMoveCountMargin = 3 + (1 << (3 * int(depth) / 8));
- const int FutilityValueMargin = 112 * bitScanReverse32(int(depth) * int(depth) / 2);
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
- // Avoid calling evaluate() if we already have the score in TT
- if (tte && (tte->type() & VALUE_TYPE_EVAL))
- futilityValue = value_from_tt(tte->value(), ply) + FutilityValueMargin;
+ // Initialize a MovePicker object for the current position
+ MovePicker mp = MovePicker(pos, ttMove, depth, H, &ss[ply], beta);
+ CheckInfo ci(pos);
- // Loop through all legal moves until no moves remain or a beta cutoff occurs
while ( bestValue < beta
&& (move = mp.get_next_move()) != MOVE_NONE
- && !thread_should_stop(threadID))
+ && !TM.thread_should_stop(threadID))
{
assert(move_is_ok(move));
if (move == excludedMove)
continue;
- singleReply = (isCheck && mp.number_of_evasions() == 1);
moveIsCheck = pos.move_is_check(move, ci);
+ singleEvasion = (isCheck && mp.number_of_evasions() == 1);
captureOrPromotion = pos.move_is_capture_or_promotion(move);
- // Decide the new search depth
- ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleReply, mateThreat, &dangerous);
+ // Step 11. Decide the new search depth
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, singleEvasion, mateThreat, &dangerous);
- // We want to extend the TT move if it is much better then remaining ones.
- // To verify this we do a reduced search on all the other moves but the ttMove,
- // if result is lower then TT value minus a margin then we assume ttMove is the
- // only one playable. It is a kind of relaxed single reply extension.
- if ( depth >= 8 * OnePly
+ // Singular extension search. We extend the TT move if its value is much better than
+ // its siblings. To verify this we do a reduced search on all the other moves but the
+ // ttMove, if result is lower then ttValue minus a margin then we extend ttMove.
+ if ( depth >= SingularExtensionDepthAtNonPVNodes
&& tte
&& move == tte->move()
&& !excludedMove // Do not allow recursive single-reply search
if (abs(ttValue) < VALUE_KNOWN_WIN)
{
- Value excValue = search(pos, ss, ttValue - SingleReplyMargin, depth / 2, ply, false, threadID, move);
+ Value excValue = search(pos, ss, ttValue - SingularExtensionMargin, depth / 2, ply, false, threadID, move);
- // If search result is well below the foreseen score of the ttMove then we
- // assume ttMove is the only one realistically playable and we extend it.
- if (excValue < ttValue - SingleReplyMargin)
+ if (excValue < ttValue - SingularExtensionMargin)
ext = OnePly;
}
}
newDepth = depth - OnePly + ext;
- // Update current move
+ // Update current move (this must be done after singular extension search)
movesSearched[moveCount++] = ss[ply].currentMove = move;
- // Futility pruning
- if ( useFutilityPruning
+ // Step 12. Futility pruning
+ if ( !isCheck
&& !dangerous
&& !captureOrPromotion
+ && !move_is_castle(move)
&& move != ttMove)
{
// Move count based pruning
- if ( moveCount >= FutilityMoveCountMargin
+ if ( moveCount >= futility_move_count(depth)
&& ok_to_prune(pos, move, ss[ply].threatMove)
&& bestValue > value_mated_in(PLY_MAX))
continue;
// Value based pruning
- if (futilityValue == VALUE_NONE)
- futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
-
- futilityValueScaled = futilityValue - moveCount * IncrementalFutilityMargin;
+ Depth predictedDepth = newDepth - nonpv_reduction(depth, moveCount); // We illogically ignore reduction condition depth >= 3*OnePly
+ futilityValueScaled = ss[ply].eval + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
if (futilityValueScaled < beta)
{
}
}
- // Make and search the move
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
+ bool doFullDepthSearch = true;
+
if ( depth >= 3*OnePly
- && moveCount >= LMRNonPVMoves
&& !dangerous
&& !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[ply]))
{
- ss[ply].reduction = OnePly;
- value = -search(pos, ss, -(beta-1), newDepth-OnePly, ply+1, true, threadID);
+ ss[ply].reduction = nonpv_reduction(depth, moveCount);
+ if (ss[ply].reduction)
+ {
+ value = -search(pos, ss, -(beta-1), newDepth-ss[ply].reduction, ply+1, true, threadID);
+ doFullDepthSearch = (value >= beta);
+ }
}
- else
- value = beta; // Just to trigger next condition
- if (value >= beta) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
ss[ply].reduction = Depth(0);
value = -search(pos, ss, -(beta-1), newDepth, ply+1, true, threadID);
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- // New best move?
+ // Step 17. Check for new best move
if (value > bestValue)
{
bestValue = value;
ss[ply].mateKiller = move;
}
- // Split?
- if ( ActiveThreads > 1
+ // Step 18. Check for split
+ if ( TM.active_threads() > 1
&& bestValue < beta
&& depth >= MinimumSplitDepth
&& Iteration <= 99
- && idle_thread_exists(threadID)
+ && TM.available_thread_exists(threadID)
&& !AbortSearch
- && !thread_should_stop(threadID)
- && split(pos, ss, ply, &beta, &beta, &bestValue, futilityValue, approximateEval,
- depth, &moveCount, &mp, threadID, false))
+ && !TM.thread_should_stop(threadID)
+ && TM.split(pos, ss, ply, NULL, beta, &bestValue,
+ depth, mateThreat, &moveCount, &mp, threadID, false))
break;
}
- // All legal moves have been searched. A special case: If there were
+ // Step 19. Check for mate and stalemate
+ // All legal moves have been searched and if there were
// no legal moves, it must be mate or stalemate.
- if (moveCount == 0)
+ // If one move was excluded return fail low.
+ if (!moveCount)
return excludedMove ? beta - 1 : (pos.is_check() ? value_mated_in(ply) : VALUE_DRAW);
+ // Step 20. Update tables
// If the search is not aborted, update the transposition table,
// history counters, and killer moves.
- if (AbortSearch || thread_should_stop(threadID))
+ if (AbortSearch || TM.thread_should_stop(threadID))
return bestValue;
if (bestValue < beta)
TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_UPPER, depth, MOVE_NONE);
else
{
- BetaCounter.add(pos.side_to_move(), depth, threadID);
+ TM.incrementBetaCounter(pos.side_to_move(), depth, threadID);
move = ss[ply].pv[ply];
+ TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
if (!pos.move_is_capture_or_promotion(move))
{
update_history(pos, move, depth, movesSearched, moveCount);
update_killers(move, ss[ply]);
}
- TT.store(posKey, value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, depth, move);
+
}
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
assert(depth <= 0);
assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ assert(threadID >= 0 && threadID < TM.active_threads());
EvalInfo ei;
StateInfo st;
Move ttMove, move;
- Value staticValue, bestValue, value, futilityValue;
- bool isCheck, enoughMaterial, moveIsCheck;
+ Value staticValue, bestValue, value, futilityBase, futilityValue;
+ bool isCheck, enoughMaterial, moveIsCheck, evasionPrunable;
const TTEntry* tte = NULL;
int moveCount = 0;
bool pvNode = (beta - alpha != 1);
+ Value oldAlpha = alpha;
// Initialize, and make an early exit in case of an aborted search,
// an instant draw, maximum ply reached, etc.
init_node(ss, ply, threadID);
// After init_node() that calls poll()
- if (AbortSearch || thread_should_stop(threadID))
+ if (AbortSearch || TM.thread_should_stop(threadID))
return Value(0);
- if (pos.is_draw())
+ if (pos.is_draw() || ply >= PLY_MAX - 1)
return VALUE_DRAW;
- // Transposition table lookup, only when not in PV
- if (!pvNode)
+ // Transposition table lookup. At PV nodes, we don't use the TT for
+ // pruning, but only for move ordering.
+ tte = TT.retrieve(pos.get_key());
+ ttMove = (tte ? tte->move() : MOVE_NONE);
+
+ if (!pvNode && tte && ok_to_use_TT(tte, depth, beta, ply))
{
- tte = TT.retrieve(pos.get_key());
- if (tte && ok_to_use_TT(tte, depth, beta, ply))
- {
- assert(tte->type() != VALUE_TYPE_EVAL);
+ assert(tte->type() != VALUE_TYPE_EVAL);
- return value_from_tt(tte->value(), ply);
- }
+ ss[ply].currentMove = ttMove; // Can be MOVE_NONE
+ return value_from_tt(tte->value(), ply);
}
- ttMove = (tte ? tte->move() : MOVE_NONE);
isCheck = pos.is_check();
- ei.futilityMargin = Value(0); // Manually initialize futilityMargin
// Evaluate the position statically
if (isCheck)
staticValue = -VALUE_INFINITE;
-
else if (tte && (tte->type() & VALUE_TYPE_EVAL))
- {
- // Use the cached evaluation score if possible
- assert(ei.futilityMargin == Value(0));
-
staticValue = value_from_tt(tte->value(), ply);
- }
else
staticValue = evaluate(pos, ei, threadID);
- if (ply >= PLY_MAX - 1)
- return pos.is_check() ? quick_evaluate(pos) : evaluate(pos, ei, threadID);
+ if (!isCheck)
+ {
+ ss[ply].eval = staticValue;
+ update_gains(pos, ss[ply - 1].currentMove, ss[ply - 1].eval, ss[ply].eval);
+ }
// Initialize "stand pat score", and return it immediately if it is
// at least beta.
if (bestValue >= beta)
{
// Store the score to avoid a future costly evaluation() call
- if (!isCheck && !tte && ei.futilityMargin == 0)
+ if (!isCheck && !tte && ei.futilityMargin[pos.side_to_move()] == 0)
TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EV_LO, Depth(-127*OnePly), MOVE_NONE);
return bestValue;
if (bestValue > alpha)
alpha = bestValue;
+ // If we are near beta then try to get a cutoff pushing checks a bit further
+ bool deepChecks = depth == -OnePly && staticValue >= beta - PawnValueMidgame / 8;
+
// Initialize a MovePicker object for the current position, and prepare
- // to search the moves. Because the depth is <= 0 here, only captures,
- // queen promotions and checks (only if depth == 0) will be generated.
- MovePicker mp = MovePicker(pos, ttMove, depth, H);
+ // to search the moves. Because the depth is <= 0 here, only captures,
+ // queen promotions and checks (only if depth == 0 or depth == -OnePly
+ // and we are near beta) will be generated.
+ MovePicker mp = MovePicker(pos, ttMove, deepChecks ? Depth(0) : depth, H);
CheckInfo ci(pos);
enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMidgame;
+ futilityBase = staticValue + FutilityMarginQS + ei.futilityMargin[pos.side_to_move()];
// Loop through the moves until no moves remain or a beta cutoff
// occurs.
{
assert(move_is_ok(move));
+ moveIsCheck = pos.move_is_check(move, ci);
+
+ // Update current move
moveCount++;
ss[ply].currentMove = move;
- moveIsCheck = pos.move_is_check(move, ci);
-
// Futility pruning
if ( enoughMaterial
&& !isCheck
&& !move_is_promotion(move)
&& !pos.move_is_passed_pawn_push(move))
{
- futilityValue = staticValue
- + Max(pos.midgame_value_of_piece_on(move_to(move)),
- pos.endgame_value_of_piece_on(move_to(move)))
- + (move_is_ep(move) ? PawnValueEndgame : Value(0))
- + FutilityMarginQS
- + ei.futilityMargin;
+ futilityValue = futilityBase
+ + pos.endgame_value_of_piece_on(move_to(move))
+ + (move_is_ep(move) ? PawnValueEndgame : Value(0));
if (futilityValue < alpha)
{
}
}
- // Don't search captures and checks with negative SEE values
- if ( !isCheck
+ // Detect blocking evasions that are candidate to be pruned
+ evasionPrunable = isCheck
+ && bestValue != -VALUE_INFINITE
+ && !pos.move_is_capture(move)
+ && pos.type_of_piece_on(move_from(move)) != KING
+ && !pos.can_castle(pos.side_to_move());
+
+ // Don't search moves with negative SEE values
+ if ( (!isCheck || evasionPrunable)
+ && !pvNode
&& move != ttMove
&& !move_is_promotion(move)
&& pos.see_sign(move) < 0)
}
}
- // All legal moves have been searched. A special case: If we're in check
+ // All legal moves have been searched. A special case: If we're in check
// and no legal moves were found, it is checkmate.
if (!moveCount && pos.is_check()) // Mate!
return value_mated_in(ply);
- assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
-
// Update transposition table
- move = ss[ply].pv[ply];
- if (!pvNode)
+ Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ if (bestValue <= oldAlpha)
+ {
+ // If bestValue isn't changed it means it is still the static evaluation
+ // of the node, so keep this info to avoid a future evaluation() call.
+ ValueType type = (bestValue == staticValue && !ei.futilityMargin[pos.side_to_move()] ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
+ }
+ else if (bestValue >= beta)
{
- // If bestValue isn't changed it means it is still the static evaluation of
- // the node, so keep this info to avoid a future costly evaluation() call.
- ValueType type = (bestValue == staticValue && !ei.futilityMargin ? VALUE_TYPE_EV_UP : VALUE_TYPE_UPPER);
- Depth d = (depth == Depth(0) ? Depth(0) : Depth(-1));
+ move = ss[ply].pv[ply];
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
- if (bestValue < beta)
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), type, d, MOVE_NONE);
- else
- TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_LOWER, d, move);
+ // Update killers only for good checking moves
+ if (!pos.move_is_capture_or_promotion(move))
+ update_killers(move, ss[ply]);
}
+ else
+ TT.store(pos.get_key(), value_to_tt(bestValue, ply), VALUE_TYPE_EXACT, d, ss[ply].pv[ply]);
- // Update killers only for good check moves
- if (alpha >= beta && !pos.move_is_capture_or_promotion(move))
- update_killers(move, ss[ply]);
+ assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
return bestValue;
}
void sp_search(SplitPoint* sp, int threadID) {
- assert(threadID >= 0 && threadID < ActiveThreads);
- assert(ActiveThreads > 1);
+ assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(TM.active_threads() > 1);
+
+ StateInfo st;
+ Move move;
+ Depth ext, newDepth;
+ Value value, futilityValueScaled;
+ bool isCheck, moveIsCheck, captureOrPromotion, dangerous;
+ int moveCount;
+ value = -VALUE_INFINITE;
- Position pos = Position(sp->pos);
+ Position pos(*sp->pos);
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
- Value value;
- Move move;
- bool isCheck = pos.is_check();
- bool useFutilityPruning = sp->depth < SelectiveDepth
- && !isCheck;
+ isCheck = pos.is_check();
- const int FutilityMoveCountMargin = 3 + (1 << (3 * int(sp->depth) / 8));
- const int FutilityValueMargin = 112 * bitScanReverse32(int(sp->depth) * int(sp->depth) / 2);
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ lock_grab(&(sp->lock));
while ( sp->bestValue < sp->beta
- && !thread_should_stop(threadID)
- && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
+ && !TM.thread_should_stop(threadID)
+ && (move = sp->mp->get_next_move()) != MOVE_NONE)
{
+ moveCount = ++sp->moves;
+ lock_release(&(sp->lock));
+
assert(move_is_ok(move));
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
- lock_grab(&(sp->lock));
- int moveCount = ++sp->moves;
- lock_release(&(sp->lock));
+ // Step 11. Decide the new search depth
+ ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
+ newDepth = sp->depth - OnePly + ext;
+ // Update current move
ss[sp->ply].currentMove = move;
- // Decide the new search depth.
- bool dangerous;
- Depth ext = extension(pos, move, false, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- Depth newDepth = sp->depth - OnePly + ext;
-
- // Prune?
- if ( useFutilityPruning
+ // Step 12. Futility pruning
+ if ( !isCheck
&& !dangerous
- && !captureOrPromotion)
+ && !captureOrPromotion
+ && !move_is_castle(move))
{
// Move count based pruning
- if ( moveCount >= FutilityMoveCountMargin
+ if ( moveCount >= futility_move_count(sp->depth)
&& ok_to_prune(pos, move, ss[sp->ply].threatMove)
&& sp->bestValue > value_mated_in(PLY_MAX))
- continue;
-
- // Value based pruning
- if (sp->futilityValue == VALUE_NONE)
{
- EvalInfo ei;
- sp->futilityValue = evaluate(pos, ei, threadID) + FutilityValueMargin;
+ lock_grab(&(sp->lock));
+ continue;
}
- Value futilityValueScaled = sp->futilityValue - moveCount * IncrementalFutilityMargin;
+ // Value based pruning
+ Depth predictedDepth = newDepth - nonpv_reduction(sp->depth, moveCount);
+ futilityValueScaled = ss[sp->ply].eval + futility_margin(predictedDepth, moveCount)
+ + H.gain(pos.piece_on(move_from(move)), move_to(move)) + 45;
if (futilityValueScaled < sp->beta)
{
- if (futilityValueScaled > sp->bestValue) // Less then 1% of cases
- {
- lock_grab(&(sp->lock));
- if (futilityValueScaled > sp->bestValue)
- sp->bestValue = futilityValueScaled;
- lock_release(&(sp->lock));
- }
+ lock_grab(&(sp->lock));
+
+ if (futilityValueScaled > sp->bestValue)
+ sp->bestValue = futilityValueScaled;
continue;
}
}
- // Make and search the move.
- StateInfo st;
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
+ bool doFullDepthSearch = true;
+
if ( !dangerous
- && moveCount >= LMRNonPVMoves
&& !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
- ss[sp->ply].reduction = OnePly;
- value = -search(pos, ss, -(sp->beta-1), newDepth - OnePly, sp->ply+1, true, threadID);
+ ss[sp->ply].reduction = nonpv_reduction(sp->depth, moveCount);
+ if (ss[sp->ply].reduction)
+ {
+ value = -search(pos, ss, -(sp->beta-1), newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
+ doFullDepthSearch = (value >= sp->beta && !TM.thread_should_stop(threadID));
+ }
}
- else
- value = sp->beta; // Just to trigger next condition
- if (value >= sp->beta) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
ss[sp->ply].reduction = Depth(0);
value = -search(pos, ss, -(sp->beta - 1), newDepth, sp->ply+1, true, threadID);
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- if (thread_should_stop(threadID))
- break;
+ // Step 17. Check for new best move
+ lock_grab(&(sp->lock));
- // New best move?
- if (value > sp->bestValue) // Less then 2% of cases
+ if (value > sp->bestValue && !TM.thread_should_stop(threadID))
{
- lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+ sp->bestValue = value;
+ if (sp->bestValue >= sp->beta)
{
- sp->bestValue = value;
- if (sp->bestValue >= sp->beta)
- {
- sp_update_pv(sp->parentSstack, ss, sp->ply);
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
-
- sp->finished = true;
- }
+ sp->stopRequest = true;
+ sp_update_pv(sp->parentSstack, ss, sp->ply);
}
- lock_release(&(sp->lock));
}
}
- lock_grab(&(sp->lock));
-
- // If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads.
- if (sp->master == threadID && thread_should_stop(threadID))
- for (int i = 0; i < ActiveThreads; i++)
- if (sp->slaves[i])
- Threads[i].stop = true;
+ /* Here we have the lock still grabbed */
- sp->cpus--;
sp->slaves[threadID] = 0;
+ sp->cpus--;
lock_release(&(sp->lock));
}
void sp_search_pv(SplitPoint* sp, int threadID) {
- assert(threadID >= 0 && threadID < ActiveThreads);
- assert(ActiveThreads > 1);
+ assert(threadID >= 0 && threadID < TM.active_threads());
+ assert(TM.active_threads() > 1);
+
+ StateInfo st;
+ Move move;
+ Depth ext, newDepth;
+ Value value;
+ bool moveIsCheck, captureOrPromotion, dangerous;
+ int moveCount;
+ value = -VALUE_INFINITE;
- Position pos = Position(sp->pos);
+ Position pos(*sp->pos);
CheckInfo ci(pos);
SearchStack* ss = sp->sstack[threadID];
- Value value;
- Move move;
+
+ // Step 10. Loop through moves
+ // Loop through all legal moves until no moves remain or a beta cutoff occurs
+ lock_grab(&(sp->lock));
while ( sp->alpha < sp->beta
- && !thread_should_stop(threadID)
- && (move = sp->mp->get_next_move(sp->lock)) != MOVE_NONE)
+ && !TM.thread_should_stop(threadID)
+ && (move = sp->mp->get_next_move()) != MOVE_NONE)
{
- bool moveIsCheck = pos.move_is_check(move, ci);
- bool captureOrPromotion = pos.move_is_capture_or_promotion(move);
+ moveCount = ++sp->moves;
+ lock_release(&(sp->lock));
assert(move_is_ok(move));
- lock_grab(&(sp->lock));
- int moveCount = ++sp->moves;
- lock_release(&(sp->lock));
+ moveIsCheck = pos.move_is_check(move, ci);
+ captureOrPromotion = pos.move_is_capture_or_promotion(move);
+
+ // Step 11. Decide the new search depth
+ ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, sp->mateThreat, &dangerous);
+ newDepth = sp->depth - OnePly + ext;
+ // Update current move
ss[sp->ply].currentMove = move;
- // Decide the new search depth.
- bool dangerous;
- Depth ext = extension(pos, move, true, captureOrPromotion, moveIsCheck, false, false, &dangerous);
- Depth newDepth = sp->depth - OnePly + ext;
+ // Step 12. Futility pruning (is omitted in PV nodes)
- // Make and search the move.
- StateInfo st;
+ // Step 13. Make the move
pos.do_move(move, st, ci, moveIsCheck);
- // Try to reduce non-pv search depth by one ply if move seems not problematic,
+ // Step 14. Reduced search
// if the move fails high will be re-searched at full depth.
+ bool doFullDepthSearch = true;
+
if ( !dangerous
- && moveCount >= LMRPVMoves
&& !captureOrPromotion
&& !move_is_castle(move)
&& !move_is_killer(move, ss[sp->ply]))
{
- ss[sp->ply].reduction = OnePly;
- value = -search(pos, ss, -sp->alpha, newDepth - OnePly, sp->ply+1, true, threadID);
+ ss[sp->ply].reduction = pv_reduction(sp->depth, moveCount);
+ if (ss[sp->ply].reduction)
+ {
+ Value localAlpha = sp->alpha;
+ value = -search(pos, ss, -localAlpha, newDepth-ss[sp->ply].reduction, sp->ply+1, true, threadID);
+ doFullDepthSearch = (value > localAlpha && !TM.thread_should_stop(threadID));
+ }
}
- else
- value = sp->alpha + 1; // Just to trigger next condition
- if (value > sp->alpha) // Go with full depth non-pv search
+ // Step 15. Full depth search
+ if (doFullDepthSearch)
{
+ Value localAlpha = sp->alpha;
ss[sp->ply].reduction = Depth(0);
- value = -search(pos, ss, -sp->alpha, newDepth, sp->ply+1, true, threadID);
+ value = -search(pos, ss, -localAlpha, newDepth, sp->ply+1, true, threadID);
- if (value > sp->alpha && value < sp->beta)
+ if (value > localAlpha && value < sp->beta && !TM.thread_should_stop(threadID))
{
- // When the search fails high at ply 1 while searching the first
- // move at the root, set the flag failHighPly1. This is used for
- // time managment: We don't want to stop the search early in
- // such cases, because resolving the fail high at ply 1 could
- // result in a big drop in score at the root.
- if (sp->ply == 1 && RootMoveNumber == 1)
- Threads[threadID].failHighPly1 = true;
-
- value = -search_pv(pos, ss, -sp->beta, -sp->alpha, newDepth, sp->ply+1, threadID);
- Threads[threadID].failHighPly1 = false;
- }
+ // If another thread has failed high then sp->alpha has been increased
+ // to be higher or equal then beta, if so, avoid to start a PV search.
+ localAlpha = sp->alpha;
+ if (localAlpha < sp->beta)
+ value = -search_pv(pos, ss, -sp->beta, -localAlpha, newDepth, sp->ply+1, threadID);
+ }
}
+
+ // Step 16. Undo move
pos.undo_move(move);
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
- if (thread_should_stop(threadID))
- break;
-
- // New best move?
+ // Step 17. Check for new best move
lock_grab(&(sp->lock));
- if (value > sp->bestValue && !thread_should_stop(threadID))
+
+ if (value > sp->bestValue && !TM.thread_should_stop(threadID))
{
sp->bestValue = value;
if (value > sp->alpha)
{
+ // Ask threads to stop before to modify sp->alpha
+ if (value >= sp->beta)
+ sp->stopRequest = true;
+
sp->alpha = value;
+
sp_update_pv(sp->parentSstack, ss, sp->ply);
if (value == value_mate_in(sp->ply + 1))
ss[sp->ply].mateKiller = move;
-
- if (value >= sp->beta)
- {
- for (int i = 0; i < ActiveThreads; i++)
- if (i != threadID && (i == sp->master || sp->slaves[i]))
- Threads[i].stop = true;
-
- sp->finished = true;
- }
- }
- // If we are at ply 1, and we are searching the first root move at
- // ply 0, set the 'Problem' variable if the score has dropped a lot
- // (from the computer's point of view) since the previous iteration.
- if ( sp->ply == 1
- && Iteration >= 2
- && -value <= IterationInfo[Iteration-1].value - ProblemMargin)
- Problem = true;
+ }
}
- lock_release(&(sp->lock));
}
- lock_grab(&(sp->lock));
-
- // If this is the master thread and we have been asked to stop because of
- // a beta cutoff higher up in the tree, stop all slave threads.
- if (sp->master == threadID && thread_should_stop(threadID))
- for (int i = 0; i < ActiveThreads; i++)
- if (sp->slaves[i])
- Threads[i].stop = true;
+ /* Here we have the lock still grabbed */
- sp->cpus--;
sp->slaves[threadID] = 0;
+ sp->cpus--;
lock_release(&(sp->lock));
}
- /// The BetaCounterType class
-
- BetaCounterType::BetaCounterType() { clear(); }
- void BetaCounterType::clear() {
-
- for (int i = 0; i < THREAD_MAX; i++)
- Threads[i].betaCutOffs[WHITE] = Threads[i].betaCutOffs[BLACK] = 0ULL;
- }
+ // init_node() is called at the beginning of all the search functions
+ // (search(), search_pv(), qsearch(), and so on) and initializes the
+ // search stack object corresponding to the current node. Once every
+ // NodesBetweenPolls nodes, init_node() also calls poll(), which polls
+ // for user input and checks whether it is time to stop the search.
- void BetaCounterType::add(Color us, Depth d, int threadID) {
+ void init_node(SearchStack ss[], int ply, int threadID) {
- // Weighted count based on depth
- Threads[threadID].betaCutOffs[us] += unsigned(d);
- }
+ assert(ply >= 0 && ply < PLY_MAX);
+ assert(threadID >= 0 && threadID < TM.active_threads());
- void BetaCounterType::read(Color us, int64_t& our, int64_t& their) {
+ TM.incrementNodeCounter(threadID);
- our = their = 0UL;
- for (int i = 0; i < THREAD_MAX; i++)
+ if (threadID == 0)
{
- our += Threads[i].betaCutOffs[us];
- their += Threads[i].betaCutOffs[opposite_color(us)];
+ NodesSincePoll++;
+ if (NodesSincePoll >= NodesBetweenPolls)
+ {
+ poll(ss, ply);
+ NodesSincePoll = 0;
+ }
}
+ ss[ply].init(ply);
+ ss[ply + 2].initKillers();
}
- /// The RootMove class
+ // update_pv() is called whenever a search returns a value > alpha.
+ // It updates the PV in the SearchStack object corresponding to the
+ // current node.
- // Constructor
+ void update_pv(SearchStack ss[], int ply) {
- RootMove::RootMove() {
- nodes = cumulativeNodes = ourBeta = theirBeta = 0ULL;
- }
+ assert(ply >= 0 && ply < PLY_MAX);
- // RootMove::operator<() is the comparison function used when
- // sorting the moves. A move m1 is considered to be better
- // than a move m2 if it has a higher score, or if the moves
- // have equal score but m1 has the higher node count.
+ int p;
- bool RootMove::operator<(const RootMove& m) {
+ ss[ply].pv[ply] = ss[ply].currentMove;
- if (score != m.score)
- return (score < m.score);
+ for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++)
+ ss[ply].pv[p] = ss[ply + 1].pv[p];
- return theirBeta <= m.theirBeta;
+ ss[ply].pv[p] = MOVE_NONE;
}
- /// The RootMoveList class
-
- // Constructor
- RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) {
-
- MoveStack mlist[MaxRootMoves];
- bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
+ // sp_update_pv() is a variant of update_pv for use at split points. The
+ // difference between the two functions is that sp_update_pv also updates
+ // the PV at the parent node.
- // Generate all legal moves
- MoveStack* last = generate_moves(pos, mlist);
+ void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) {
- // Add each move to the moves[] array
- for (MoveStack* cur = mlist; cur != last; cur++)
- {
- bool includeMove = includeAllMoves;
+ assert(ply >= 0 && ply < PLY_MAX);
- for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
- includeMove = (searchMoves[k] == cur->move);
+ int p;
- if (!includeMove)
- continue;
+ ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove;
- // Find a quick score for the move
- StateInfo st;
- SearchStack ss[PLY_MAX_PLUS_2];
- init_ss_array(ss);
+ for (p = ply + 1; ss[ply + 1].pv[p] != MOVE_NONE; p++)
+ ss[ply].pv[p] = pss[ply].pv[p] = ss[ply + 1].pv[p];
- moves[count].move = cur->move;
- pos.do_move(moves[count].move, st);
- moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
- pos.undo_move(moves[count].move);
- moves[count].pv[0] = moves[count].move;
- moves[count].pv[1] = MOVE_NONE;
- count++;
- }
- sort();
+ ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE;
}
- // Simple accessor methods for the RootMoveList class
-
- inline Move RootMoveList::get_move(int moveNum) const {
- return moves[moveNum].move;
- }
-
- inline Value RootMoveList::get_move_score(int moveNum) const {
- return moves[moveNum].score;
- }
+ // connected_moves() tests whether two moves are 'connected' in the sense
+ // that the first move somehow made the second move possible (for instance
+ // if the moving piece is the same in both moves). The first move is assumed
+ // to be the move that was made to reach the current position, while the
+ // second move is assumed to be a move from the current position.
- inline void RootMoveList::set_move_score(int moveNum, Value score) {
- moves[moveNum].score = score;
- }
+ bool connected_moves(const Position& pos, Move m1, Move m2) {
- inline void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) {
- moves[moveNum].nodes = nodes;
- moves[moveNum].cumulativeNodes += nodes;
- }
+ Square f1, t1, f2, t2;
+ Piece p;
- inline void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
- moves[moveNum].ourBeta = our;
- moves[moveNum].theirBeta = their;
- }
+ assert(move_is_ok(m1));
+ assert(move_is_ok(m2));
- void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
- int j;
- for(j = 0; pv[j] != MOVE_NONE; j++)
- moves[moveNum].pv[j] = pv[j];
- moves[moveNum].pv[j] = MOVE_NONE;
- }
+ if (m2 == MOVE_NONE)
+ return false;
- inline Move RootMoveList::get_move_pv(int moveNum, int i) const {
- return moves[moveNum].pv[i];
- }
-
- inline int64_t RootMoveList::get_move_cumulative_nodes(int moveNum) const {
- return moves[moveNum].cumulativeNodes;
- }
-
- inline int RootMoveList::move_count() const {
- return count;
- }
-
-
- // RootMoveList::sort() sorts the root move list at the beginning of a new
- // iteration.
-
- inline void RootMoveList::sort() {
-
- sort_multipv(count - 1); // all items
- }
-
-
- // RootMoveList::sort_multipv() sorts the first few moves in the root move
- // list by their scores and depths. It is used to order the different PVs
- // correctly in MultiPV mode.
-
- void RootMoveList::sort_multipv(int n) {
-
- for (int i = 1; i <= n; i++)
- {
- RootMove rm = moves[i];
- int j;
- for (j = i; j > 0 && moves[j-1] < rm; j--)
- moves[j] = moves[j-1];
- moves[j] = rm;
- }
- }
-
-
- // init_node() is called at the beginning of all the search functions
- // (search(), search_pv(), qsearch(), and so on) and initializes the search
- // stack object corresponding to the current node. Once every
- // NodesBetweenPolls nodes, init_node() also calls poll(), which polls
- // for user input and checks whether it is time to stop the search.
-
- void init_node(SearchStack ss[], int ply, int threadID) {
-
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
-
- Threads[threadID].nodes++;
-
- if (threadID == 0)
- {
- NodesSincePoll++;
- if (NodesSincePoll >= NodesBetweenPolls)
- {
- poll();
- NodesSincePoll = 0;
- }
- }
- ss[ply].init(ply);
- ss[ply+2].initKillers();
-
- if (Threads[threadID].printCurrentLine)
- print_current_line(ss, ply, threadID);
- }
-
-
- // update_pv() is called whenever a search returns a value > alpha. It
- // updates the PV in the SearchStack object corresponding to the current
- // node.
-
- void update_pv(SearchStack ss[], int ply) {
- assert(ply >= 0 && ply < PLY_MAX);
-
- ss[ply].pv[ply] = ss[ply].currentMove;
- int p;
- for(p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++)
- ss[ply].pv[p] = ss[ply+1].pv[p];
- ss[ply].pv[p] = MOVE_NONE;
- }
-
-
- // sp_update_pv() is a variant of update_pv for use at split points. The
- // difference between the two functions is that sp_update_pv also updates
- // the PV at the parent node.
-
- void sp_update_pv(SearchStack* pss, SearchStack ss[], int ply) {
- assert(ply >= 0 && ply < PLY_MAX);
-
- ss[ply].pv[ply] = pss[ply].pv[ply] = ss[ply].currentMove;
- int p;
- for(p = ply + 1; ss[ply+1].pv[p] != MOVE_NONE; p++)
- ss[ply].pv[p] = pss[ply].pv[p] = ss[ply+1].pv[p];
- ss[ply].pv[p] = pss[ply].pv[p] = MOVE_NONE;
- }
-
-
- // connected_moves() tests whether two moves are 'connected' in the sense
- // that the first move somehow made the second move possible (for instance
- // if the moving piece is the same in both moves). The first move is
- // assumed to be the move that was made to reach the current position, while
- // the second move is assumed to be a move from the current position.
-
- bool connected_moves(const Position& pos, Move m1, Move m2) {
-
- Square f1, t1, f2, t2;
- Piece p;
-
- assert(move_is_ok(m1));
- assert(move_is_ok(m2));
-
- if (m2 == MOVE_NONE)
- return false;
-
- // Case 1: The moving piece is the same in both moves
- f2 = move_from(m2);
- t1 = move_to(m1);
- if (f2 == t1)
- return true;
+ // Case 1: The moving piece is the same in both moves
+ f2 = move_from(m2);
+ t1 = move_to(m1);
+ if (f2 == t1)
+ return true;
// Case 2: The destination square for m2 was vacated by m1
t2 = move_to(m2);
&& bit_is_set(squares_between(f2, t2), f1))
return true;
- // Case 4: The destination square for m2 is attacked by the moving piece in m1
+ // Case 4: The destination square for m2 is defended by the moving piece in m1
p = pos.piece_on(t1);
if (bit_is_set(pos.attacks_from(p, t1), t2))
return true;
// Case 5: Discovered check, checking piece is the piece moved in m1
- if ( piece_is_slider(p)
- && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2)
+ if ( piece_is_slider(p)
+ && bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), f2)
&& !bit_is_set(squares_between(t1, pos.king_square(pos.side_to_move())), t2))
{
- Bitboard occ = pos.occupied_squares();
- Color us = pos.side_to_move();
- Square ksq = pos.king_square(us);
- clear_bit(&occ, f2);
- if (type_of_piece(p) == BISHOP)
- {
- if (bit_is_set(bishop_attacks_bb(ksq, occ), t1))
- return true;
- }
- else if (type_of_piece(p) == ROOK)
- {
- if (bit_is_set(rook_attacks_bb(ksq, occ), t1))
- return true;
- }
- else
- {
- assert(type_of_piece(p) == QUEEN);
- if (bit_is_set(queen_attacks_bb(ksq, occ), t1))
- return true;
- }
+ // discovered_check_candidates() works also if the Position's side to
+ // move is the opposite of the checking piece.
+ Color them = opposite_color(pos.side_to_move());
+ Bitboard dcCandidates = pos.discovered_check_candidates(them);
+
+ if (bit_is_set(dcCandidates, f2))
+ return true;
}
return false;
}
// extension() decides whether a move should be searched with normal depth,
- // or with extended depth. Certain classes of moves (checking moves, in
+ // or with extended depth. Certain classes of moves (checking moves, in
// particular) are searched with bigger depth than ordinary moves and in
// any case are marked as 'dangerous'. Note that also if a move is not
// extended, as example because the corresponding UCI option is set to zero,
// the move is marked as 'dangerous' so, at least, we avoid to prune it.
Depth extension(const Position& pos, Move m, bool pvNode, bool captureOrPromotion,
- bool check, bool singleReply, bool mateThreat, bool* dangerous) {
+ bool moveIsCheck, bool singleEvasion, bool mateThreat, bool* dangerous) {
assert(m != MOVE_NONE);
Depth result = Depth(0);
- *dangerous = check | singleReply | mateThreat;
+ *dangerous = moveIsCheck | singleEvasion | mateThreat;
if (*dangerous)
{
- if (check)
+ if (moveIsCheck)
result += CheckExtension[pvNode];
- if (singleReply)
- result += SingleReplyExtension[pvNode];
+ if (singleEvasion)
+ result += SingleEvasionExtension[pvNode];
if (mateThreat)
result += MateThreatExtension[pvNode];
// ok_to_do_nullmove() looks at the current position and decides whether
- // doing a 'null move' should be allowed. In order to avoid zugzwang
+ // doing a 'null move' should be allowed. In order to avoid zugzwang
// problems, null moves are not allowed when the side to move has very
- // little material left. Currently, the test is a bit too simple: Null
- // moves are avoided only when the side to move has only pawns left. It's
- // probably a good idea to avoid null moves in at least some more
+ // little material left. Currently, the test is a bit too simple: Null
+ // moves are avoided only when the side to move has only pawns left.
+ // It's probably a good idea to avoid null moves in at least some more
// complicated endgames, e.g. KQ vs KR. FIXME
bool ok_to_do_nullmove(const Position& pos) {
}
- // ok_to_prune() tests whether it is safe to forward prune a move. Only
+ // ok_to_prune() tests whether it is safe to forward prune a move. Only
// non-tactical moves late in the move list close to the leaves are
// candidates for pruning.
Square mfrom, mto, tfrom, tto;
+ // Prune if there isn't any threat move
+ if (threat == MOVE_NONE)
+ return true;
+
mfrom = move_from(m);
mto = move_to(m);
tfrom = move_from(threat);
tto = move_to(threat);
- // Case 1: Castling moves are never pruned
- if (move_is_castle(m))
- return false;
-
- // Case 2: Don't prune moves which move the threatened piece
- if (!PruneEscapeMoves && threat != MOVE_NONE && mfrom == tto)
+ // Case 1: Don't prune moves which move the threatened piece
+ if (mfrom == tto)
return false;
- // Case 3: If the threatened piece has value less than or equal to the
+ // Case 2: If the threatened piece has value less than or equal to the
// value of the threatening piece, don't prune move which defend it.
- if ( !PruneDefendingMoves
- && threat != MOVE_NONE
- && pos.move_is_capture(threat)
+ if ( pos.move_is_capture(threat)
&& ( pos.midgame_value_of_piece_on(tfrom) >= pos.midgame_value_of_piece_on(tto)
|| pos.type_of_piece_on(tfrom) == KING)
&& pos.move_attacks_square(m, tto))
return false;
- // Case 4: If the moving piece in the threatened move is a slider, don't
+ // Case 3: If the moving piece in the threatened move is a slider, don't
// prune safe moves which block its ray.
- if ( !PruneBlockingMoves
- && threat != MOVE_NONE
- && piece_is_slider(pos.piece_on(tfrom))
+ if ( piece_is_slider(pos.piece_on(tfrom))
&& bit_is_set(squares_between(tfrom, tto), mto)
&& pos.see_sign(m) >= 0)
return false;
}
+ // refine_eval() returns the transposition table score if
+ // possible otherwise falls back on static position evaluation.
+
+ Value refine_eval(const TTEntry* tte, Value defaultEval, int ply) {
+
+ if (!tte)
+ return defaultEval;
+
+ Value v = value_from_tt(tte->value(), ply);
+
+ if ( (is_lower_bound(tte->type()) && v >= defaultEval)
+ || (is_upper_bound(tte->type()) && v < defaultEval))
+ return v;
+
+ return defaultEval;
+ }
+
+
// update_history() registers a good move that produced a beta-cutoff
// in history and marks as failures all the other moves of that ply.
- void update_history(const Position& pos, Move m, Depth depth,
+ void update_history(const Position& pos, Move move, Depth depth,
Move movesSearched[], int moveCount) {
- H.success(pos.piece_on(move_from(m)), move_to(m), depth);
+ Move m;
+
+ H.success(pos.piece_on(move_from(move)), move_to(move), depth);
for (int i = 0; i < moveCount - 1; i++)
{
- assert(m != movesSearched[i]);
- if (!pos.move_is_capture_or_promotion(movesSearched[i]))
- H.failure(pos.piece_on(move_from(movesSearched[i])), move_to(movesSearched[i]), depth);
+ m = movesSearched[i];
+
+ assert(m != move);
+
+ if (!pos.move_is_capture_or_promotion(m))
+ H.failure(pos.piece_on(move_from(m)), move_to(m), depth);
}
}
}
- // fail_high_ply_1() checks if some thread is currently resolving a fail
- // high at ply 1 at the node below the first root node. This information
- // is used for time managment.
-
- bool fail_high_ply_1() {
+ // update_gains() updates the gains table of a non-capture move given
+ // the static position evaluation before and after the move.
- for(int i = 0; i < ActiveThreads; i++)
- if (Threads[i].failHighPly1)
- return true;
+ void update_gains(const Position& pos, Move m, Value before, Value after) {
- return false;
+ if ( m != MOVE_NULL
+ && before != VALUE_NONE
+ && after != VALUE_NONE
+ && pos.captured_piece() == NO_PIECE_TYPE
+ && !move_is_castle(m)
+ && !move_is_promotion(m))
+ H.set_gain(pos.piece_on(move_to(m)), move_to(m), -(before + after));
}
// since the beginning of the current search.
int current_search_time() {
+
return get_system_time() - SearchStartTime;
}
// nps() computes the current nodes/second count.
int nps() {
+
int t = current_search_time();
- return (t > 0)? int((nodes_searched() * 1000) / t) : 0;
+ return (t > 0 ? int((TM.nodes_searched() * 1000) / t) : 0);
}
- // poll() performs two different functions: It polls for user input, and it
+ // poll() performs two different functions: It polls for user input, and it
// looks at the time consumed so far and decides if it's time to abort the
// search.
- void poll() {
+ void poll(SearchStack ss[], int ply) {
static int lastInfoTime;
int t = current_search_time();
{
// We are line oriented, don't read single chars
std::string command;
+
if (!std::getline(std::cin, command))
command = "quit";
else if (command == "ponderhit")
ponderhit();
}
+
// Print search information
if (t < 1000)
lastInfoTime = 0;
else if (t - lastInfoTime >= 1000)
{
lastInfoTime = t;
- lock_grab(&IOLock);
+
if (dbg_show_mean)
dbg_print_mean();
if (dbg_show_hit_rate)
dbg_print_hit_rate();
- std::cout << "info nodes " << nodes_searched() << " nps " << nps()
- << " time " << t << " hashfull " << TT.full() << std::endl;
- lock_release(&IOLock);
- if (ShowCurrentLine)
- Threads[0].printCurrentLine = true;
+ cout << "info nodes " << TM.nodes_searched() << " nps " << nps()
+ << " time " << t << " hashfull " << TT.full() << endl;
+
+ // We only support current line printing in single thread mode
+ if (ShowCurrentLine && TM.active_threads() == 1)
+ {
+ cout << "info currline";
+ for (int p = 0; p < ply; p++)
+ cout << " " << ss[p].currentMove;
+
+ cout << endl;
+ }
}
+
// Should we stop the search?
if (PonderSearch)
return;
- bool overTime = t > AbsoluteMaxSearchTime
- || (RootMoveNumber == 1 && t > MaxSearchTime + ExtraSearchTime && !FailLow) //FIXME: We are not checking any problem flags, BUG?
- || ( !FailHigh && !FailLow && !fail_high_ply_1() && !Problem
- && t > 6*(MaxSearchTime + ExtraSearchTime));
+ bool stillAtFirstMove = FirstRootMove
+ && !AspirationFailLow
+ && t > MaxSearchTime + ExtraSearchTime;
- if ( (Iteration >= 3 && (!InfiniteSearch && overTime))
+ bool noMoreTime = t > AbsoluteMaxSearchTime
+ || stillAtFirstMove;
+
+ if ( (Iteration >= 3 && UseTimeManagement && noMoreTime)
|| (ExactMaxTime && t >= ExactMaxTime)
- || (Iteration >= 3 && MaxNodes && nodes_searched() >= MaxNodes))
+ || (Iteration >= 3 && MaxNodes && TM.nodes_searched() >= MaxNodes))
AbortSearch = true;
}
int t = current_search_time();
PonderSearch = false;
- if (Iteration >= 3 &&
- (!InfiniteSearch && (StopOnPonderhit ||
- t > AbsoluteMaxSearchTime ||
- (RootMoveNumber == 1 &&
- t > MaxSearchTime + ExtraSearchTime && !FailLow) ||
- (!FailHigh && !FailLow && !fail_high_ply_1() && !Problem &&
- t > 6*(MaxSearchTime + ExtraSearchTime)))))
- AbortSearch = true;
- }
-
- // print_current_line() prints the current line of search for a given
- // thread. Called when the UCI option UCI_ShowCurrLine is 'true'.
+ bool stillAtFirstMove = FirstRootMove
+ && !AspirationFailLow
+ && t > MaxSearchTime + ExtraSearchTime;
- void print_current_line(SearchStack ss[], int ply, int threadID) {
-
- assert(ply >= 0 && ply < PLY_MAX);
- assert(threadID >= 0 && threadID < ActiveThreads);
+ bool noMoreTime = t > AbsoluteMaxSearchTime
+ || stillAtFirstMove;
- if (!Threads[threadID].idle)
- {
- lock_grab(&IOLock);
- std::cout << "info currline " << (threadID + 1);
- for (int p = 0; p < ply; p++)
- std::cout << " " << ss[p].currentMove;
-
- std::cout << std::endl;
- lock_release(&IOLock);
- }
- Threads[threadID].printCurrentLine = false;
- if (threadID + 1 < ActiveThreads)
- Threads[threadID + 1].printCurrentLine = true;
+ if (Iteration >= 3 && UseTimeManagement && (noMoreTime || StopOnPonderhit))
+ AbortSearch = true;
}
// wait_for_stop_or_ponderhit() is called when the maximum depth is reached
- // while the program is pondering. The point is to work around a wrinkle in
- // the UCI protocol: When pondering, the engine is not allowed to give a
+ // while the program is pondering. The point is to work around a wrinkle in
+ // the UCI protocol: When pondering, the engine is not allowed to give a
// "bestmove" before the GUI sends it a "stop" or "ponderhit" command.
// We simply wait here until one of these commands is sent, and return,
// after which the bestmove and pondermove will be printed (in id_loop()).
}
+ // print_pv_info() prints to standard output and eventually to log file information on
+ // the current PV line. It is called at each iteration or after a new pv is found.
+
+ void print_pv_info(const Position& pos, SearchStack ss[], Value alpha, Value beta, Value value) {
+
+ cout << "info depth " << Iteration
+ << " score " << value_to_string(value)
+ << ((value >= beta) ? " lowerbound" :
+ ((value <= alpha)? " upperbound" : ""))
+ << " time " << current_search_time()
+ << " nodes " << TM.nodes_searched()
+ << " nps " << nps()
+ << " pv ";
+
+ for (int j = 0; ss[0].pv[j] != MOVE_NONE && j < PLY_MAX; j++)
+ cout << ss[0].pv[j] << " ";
+
+ cout << endl;
+
+ if (UseLogFile)
+ {
+ ValueType type = (value >= beta ? VALUE_TYPE_LOWER
+ : (value <= alpha ? VALUE_TYPE_UPPER : VALUE_TYPE_EXACT));
+
+ LogFile << pretty_pv(pos, current_search_time(), Iteration,
+ TM.nodes_searched(), value, type, ss[0].pv) << endl;
+ }
+ }
+
+
+ // init_thread() is the function which is called when a new thread is
+ // launched. It simply calls the idle_loop() function with the supplied
+ // threadID. There are two versions of this function; one for POSIX
+ // threads and one for Windows threads.
+
+#if !defined(_MSC_VER)
+
+ void* init_thread(void *threadID) {
+
+ TM.idle_loop(*(int*)threadID, NULL);
+ return NULL;
+ }
+
+#else
+
+ DWORD WINAPI init_thread(LPVOID threadID) {
+
+ TM.idle_loop(*(int*)threadID, NULL);
+ return 0;
+ }
+
+#endif
+
+
+ /// The ThreadsManager class
+
+ // resetNodeCounters(), resetBetaCounters(), searched_nodes() and
+ // get_beta_counters() are getters/setters for the per thread
+ // counters used to sort the moves at root.
+
+ void ThreadsManager::resetNodeCounters() {
+
+ for (int i = 0; i < MAX_THREADS; i++)
+ threads[i].nodes = 0ULL;
+ }
+
+ void ThreadsManager::resetBetaCounters() {
+
+ for (int i = 0; i < MAX_THREADS; i++)
+ threads[i].betaCutOffs[WHITE] = threads[i].betaCutOffs[BLACK] = 0ULL;
+ }
+
+ int64_t ThreadsManager::nodes_searched() const {
+
+ int64_t result = 0ULL;
+ for (int i = 0; i < ActiveThreads; i++)
+ result += threads[i].nodes;
+
+ return result;
+ }
+
+ void ThreadsManager::get_beta_counters(Color us, int64_t& our, int64_t& their) const {
+
+ our = their = 0UL;
+ for (int i = 0; i < MAX_THREADS; i++)
+ {
+ our += threads[i].betaCutOffs[us];
+ their += threads[i].betaCutOffs[opposite_color(us)];
+ }
+ }
+
+
// idle_loop() is where the threads are parked when they have no work to do.
// The parameter "waitSp", if non-NULL, is a pointer to an active SplitPoint
// object for which the current thread is the master.
- void idle_loop(int threadID, SplitPoint* waitSp) {
- assert(threadID >= 0 && threadID < THREAD_MAX);
+ void ThreadsManager::idle_loop(int threadID, SplitPoint* waitSp) {
+
+ assert(threadID >= 0 && threadID < MAX_THREADS);
- Threads[threadID].running = true;
+ while (true)
+ {
+ // Slave threads can exit as soon as AllThreadsShouldExit raises,
+ // master should exit as last one.
+ if (AllThreadsShouldExit)
+ {
+ assert(!waitSp);
+ threads[threadID].state = THREAD_TERMINATED;
+ return;
+ }
- while(true) {
- if(AllThreadsShouldExit && threadID != 0)
- break;
+ // If we are not thinking, wait for a condition to be signaled
+ // instead of wasting CPU time polling for work.
+ while (AllThreadsShouldSleep || threadID >= ActiveThreads)
+ {
+ assert(!waitSp);
+ assert(threadID != 0);
+ threads[threadID].state = THREAD_SLEEPING;
- // If we are not thinking, wait for a condition to be signaled instead
- // of wasting CPU time polling for work:
- while(threadID != 0 && (Idle || threadID >= ActiveThreads)) {
#if !defined(_MSC_VER)
- pthread_mutex_lock(&WaitLock);
- if(Idle || threadID >= ActiveThreads)
- pthread_cond_wait(&WaitCond, &WaitLock);
- pthread_mutex_unlock(&WaitLock);
+ lock_grab(&WaitLock);
+ if (AllThreadsShouldSleep || threadID >= ActiveThreads)
+ pthread_cond_wait(&WaitCond, &WaitLock);
+ lock_release(&WaitLock);
#else
- WaitForSingleObject(SitIdleEvent[threadID], INFINITE);
+ WaitForSingleObject(SitIdleEvent[threadID], INFINITE);
#endif
- }
+ }
- // If this thread has been assigned work, launch a search
- if(Threads[threadID].workIsWaiting) {
- Threads[threadID].workIsWaiting = false;
- if(Threads[threadID].splitPoint->pvNode)
- sp_search_pv(Threads[threadID].splitPoint, threadID);
- else
- sp_search(Threads[threadID].splitPoint, threadID);
- Threads[threadID].idle = true;
- }
+ // If thread has just woken up, mark it as available
+ if (threads[threadID].state == THREAD_SLEEPING)
+ threads[threadID].state = THREAD_AVAILABLE;
- // If this thread is the master of a split point and all threads have
- // finished their work at this split point, return from the idle loop.
- if(waitSp != NULL && waitSp->cpus == 0)
- return;
- }
+ // If this thread has been assigned work, launch a search
+ if (threads[threadID].state == THREAD_WORKISWAITING)
+ {
+ assert(!AllThreadsShouldExit && !AllThreadsShouldSleep);
+
+ threads[threadID].state = THREAD_SEARCHING;
+
+ if (threads[threadID].splitPoint->pvNode)
+ sp_search_pv(threads[threadID].splitPoint, threadID);
+ else
+ sp_search(threads[threadID].splitPoint, threadID);
+
+ assert(threads[threadID].state == THREAD_SEARCHING);
+
+ threads[threadID].state = THREAD_AVAILABLE;
+ }
+
+ // If this thread is the master of a split point and all threads have
+ // finished their work at this split point, return from the idle loop.
+ if (waitSp != NULL && waitSp->cpus == 0)
+ {
+ assert(threads[threadID].state == THREAD_AVAILABLE);
- Threads[threadID].running = false;
+ threads[threadID].state = THREAD_SEARCHING;
+ return;
+ }
+ }
}
- // init_split_point_stack() is called during program initialization, and
- // initializes all split point objects.
+ // init_threads() is called during startup. It launches all helper threads,
+ // and initializes the split point stack and the global locks and condition
+ // objects.
- void init_split_point_stack() {
- for(int i = 0; i < THREAD_MAX; i++)
- for(int j = 0; j < MaxActiveSplitPoints; j++) {
- SplitPointStack[i][j].parent = NULL;
- lock_init(&(SplitPointStack[i][j].lock), NULL);
- }
+ void ThreadsManager::init_threads() {
+
+ volatile int i;
+ bool ok;
+
+#if !defined(_MSC_VER)
+ pthread_t pthread[1];
+#endif
+
+ // Initialize global locks
+ lock_init(&MPLock, NULL);
+ lock_init(&WaitLock, NULL);
+
+#if !defined(_MSC_VER)
+ pthread_cond_init(&WaitCond, NULL);
+#else
+ for (i = 0; i < MAX_THREADS; i++)
+ SitIdleEvent[i] = CreateEvent(0, FALSE, FALSE, 0);
+#endif
+
+ // Initialize SplitPointStack locks
+ for (i = 0; i < MAX_THREADS; i++)
+ for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
+ {
+ SplitPointStack[i][j].parent = NULL;
+ lock_init(&(SplitPointStack[i][j].lock), NULL);
+ }
+
+ // Will be set just before program exits to properly end the threads
+ AllThreadsShouldExit = false;
+
+ // Threads will be put to sleep as soon as created
+ AllThreadsShouldSleep = true;
+
+ // All threads except the main thread should be initialized to THREAD_AVAILABLE
+ ActiveThreads = 1;
+ threads[0].state = THREAD_SEARCHING;
+ for (i = 1; i < MAX_THREADS; i++)
+ threads[i].state = THREAD_AVAILABLE;
+
+ // Launch the helper threads
+ for (i = 1; i < MAX_THREADS; i++)
+ {
+
+#if !defined(_MSC_VER)
+ ok = (pthread_create(pthread, NULL, init_thread, (void*)(&i)) == 0);
+#else
+ ok = (CreateThread(NULL, 0, init_thread, (LPVOID)(&i), 0, NULL) != NULL);
+#endif
+
+ if (!ok)
+ {
+ cout << "Failed to create thread number " << i << endl;
+ Application::exit_with_failure();
+ }
+
+ // Wait until the thread has finished launching and is gone to sleep
+ while (threads[i].state != THREAD_SLEEPING);
+ }
}
- // destroy_split_point_stack() is called when the program exits, and
- // destroys all locks in the precomputed split point objects.
+ // exit_threads() is called when the program exits. It makes all the
+ // helper threads exit cleanly.
+
+ void ThreadsManager::exit_threads() {
+
+ ActiveThreads = MAX_THREADS; // HACK
+ AllThreadsShouldSleep = true; // HACK
+ wake_sleeping_threads();
+
+ // This makes the threads to exit idle_loop()
+ AllThreadsShouldExit = true;
+
+ // Wait for thread termination
+ for (int i = 1; i < MAX_THREADS; i++)
+ while (threads[i].state != THREAD_TERMINATED);
+
+ // Now we can safely destroy the locks
+ for (int i = 0; i < MAX_THREADS; i++)
+ for (int j = 0; j < ACTIVE_SPLIT_POINTS_MAX; j++)
+ lock_destroy(&(SplitPointStack[i][j].lock));
- void destroy_split_point_stack() {
- for(int i = 0; i < THREAD_MAX; i++)
- for(int j = 0; j < MaxActiveSplitPoints; j++)
- lock_destroy(&(SplitPointStack[i][j].lock));
+ lock_destroy(&WaitLock);
+ lock_destroy(&MPLock);
}
- // thread_should_stop() checks whether the thread with a given threadID has
- // been asked to stop, directly or indirectly. This can happen if a beta
- // cutoff has occured in thre thread's currently active split point, or in
- // some ancestor of the current split point.
+ // thread_should_stop() checks whether the thread should stop its search.
+ // This can happen if a beta cutoff has occurred in the thread's currently
+ // active split point, or in some ancestor of the current split point.
+
+ bool ThreadsManager::thread_should_stop(int threadID) const {
- bool thread_should_stop(int threadID) {
assert(threadID >= 0 && threadID < ActiveThreads);
SplitPoint* sp;
- if(Threads[threadID].stop)
- return true;
- if(ActiveThreads <= 2)
- return false;
- for(sp = Threads[threadID].splitPoint; sp != NULL; sp = sp->parent)
- if(sp->finished) {
- Threads[threadID].stop = true;
- return true;
- }
- return false;
+ for (sp = threads[threadID].splitPoint; sp && !sp->stopRequest; sp = sp->parent);
+ return sp != NULL;
}
// thread_is_available() checks whether the thread with threadID "slave" is
- // available to help the thread with threadID "master" at a split point. An
- // obvious requirement is that "slave" must be idle. With more than two
+ // available to help the thread with threadID "master" at a split point. An
+ // obvious requirement is that "slave" must be idle. With more than two
// threads, this is not by itself sufficient: If "slave" is the master of
// some active split point, it is only available as a slave to the other
// threads which are busy searching the split point at the top of "slave"'s
// split point stack (the "helpful master concept" in YBWC terminology).
- bool thread_is_available(int slave, int master) {
+ bool ThreadsManager::thread_is_available(int slave, int master) const {
+
assert(slave >= 0 && slave < ActiveThreads);
assert(master >= 0 && master < ActiveThreads);
assert(ActiveThreads > 1);
- if(!Threads[slave].idle || slave == master)
- return false;
+ if (threads[slave].state != THREAD_AVAILABLE || slave == master)
+ return false;
- if(Threads[slave].activeSplitPoints == 0)
- // No active split points means that the thread is available as a slave
- // for any other thread.
- return true;
+ // Make a local copy to be sure doesn't change under our feet
+ int localActiveSplitPoints = threads[slave].activeSplitPoints;
- if(ActiveThreads == 2)
- return true;
+ if (localActiveSplitPoints == 0)
+ // No active split points means that the thread is available as
+ // a slave for any other thread.
+ return true;
- // Apply the "helpful master" concept if possible.
- if(SplitPointStack[slave][Threads[slave].activeSplitPoints-1].slaves[master])
- return true;
+ if (ActiveThreads == 2)
+ return true;
+
+ // Apply the "helpful master" concept if possible. Use localActiveSplitPoints
+ // that is known to be > 0, instead of threads[slave].activeSplitPoints that
+ // could have been set to 0 by another thread leading to an out of bound access.
+ if (SplitPointStack[slave][localActiveSplitPoints - 1].slaves[master])
+ return true;
return false;
}
- // idle_thread_exists() tries to find an idle thread which is available as
+ // available_thread_exists() tries to find an idle thread which is available as
// a slave for the thread with threadID "master".
- bool idle_thread_exists(int master) {
+ bool ThreadsManager::available_thread_exists(int master) const {
+
assert(master >= 0 && master < ActiveThreads);
assert(ActiveThreads > 1);
- for(int i = 0; i < ActiveThreads; i++)
- if(thread_is_available(i, master))
- return true;
+ for (int i = 0; i < ActiveThreads; i++)
+ if (thread_is_available(i, master))
+ return true;
+
return false;
}
// split() does the actual work of distributing the work at a node between
- // several threads at PV nodes. If it does not succeed in splitting the
+ // several threads at PV nodes. If it does not succeed in splitting the
// node (because no idle threads are available, or because we have no unused
- // split point objects), the function immediately returns false. If
+ // split point objects), the function immediately returns false. If
// splitting is possible, a SplitPoint object is initialized with all the
// data that must be copied to the helper threads (the current position and
// search stack, alpha, beta, the search depth, etc.), and we tell our
- // helper threads that they have been assigned work. This will cause them
- // to instantly leave their idle loops and call sp_search_pv(). When all
+ // helper threads that they have been assigned work. This will cause them
+ // to instantly leave their idle loops and call sp_search_pv(). When all
// threads have returned from sp_search_pv (or, equivalently, when
// splitPoint->cpus becomes 0), split() returns true.
- bool split(const Position& p, SearchStack* sstck, int ply,
- Value* alpha, Value* beta, Value* bestValue, const Value futilityValue,
- const Value approximateEval, Depth depth, int* moves,
- MovePicker* mp, int master, bool pvNode) {
+ bool ThreadsManager::split(const Position& p, SearchStack* sstck, int ply,
+ Value* alpha, const Value beta, Value* bestValue,
+ Depth depth, bool mateThreat, int* moves, MovePicker* mp, int master, bool pvNode) {
assert(p.is_ok());
assert(sstck != NULL);
assert(ply >= 0 && ply < PLY_MAX);
- assert(*bestValue >= -VALUE_INFINITE && *bestValue <= *alpha);
- assert(!pvNode || *alpha < *beta);
- assert(*beta <= VALUE_INFINITE);
+ assert(*bestValue >= -VALUE_INFINITE);
+ assert( ( pvNode && *bestValue <= *alpha)
+ || (!pvNode && *bestValue < beta ));
+ assert(!pvNode || *alpha < beta);
+ assert(beta <= VALUE_INFINITE);
assert(depth > Depth(0));
assert(master >= 0 && master < ActiveThreads);
assert(ActiveThreads > 1);
SplitPoint* splitPoint;
- int i;
lock_grab(&MPLock);
// If no other thread is available to help us, or if we have too many
// active split points, don't split.
- if(!idle_thread_exists(master) ||
- Threads[master].activeSplitPoints >= MaxActiveSplitPoints) {
- lock_release(&MPLock);
- return false;
+ if ( !available_thread_exists(master)
+ || threads[master].activeSplitPoints >= ACTIVE_SPLIT_POINTS_MAX)
+ {
+ lock_release(&MPLock);
+ return false;
}
// Pick the next available split point object from the split point stack
- splitPoint = SplitPointStack[master] + Threads[master].activeSplitPoints;
- Threads[master].activeSplitPoints++;
+ splitPoint = &SplitPointStack[master][threads[master].activeSplitPoints];
// Initialize the split point object
- splitPoint->parent = Threads[master].splitPoint;
- splitPoint->finished = false;
+ splitPoint->parent = threads[master].splitPoint;
+ splitPoint->stopRequest = false;
splitPoint->ply = ply;
splitPoint->depth = depth;
- splitPoint->alpha = pvNode? *alpha : (*beta - 1);
- splitPoint->beta = *beta;
+ splitPoint->mateThreat = mateThreat;
+ splitPoint->alpha = pvNode ? *alpha : beta - 1;
+ splitPoint->beta = beta;
splitPoint->pvNode = pvNode;
splitPoint->bestValue = *bestValue;
- splitPoint->futilityValue = futilityValue;
- splitPoint->approximateEval = approximateEval;
splitPoint->master = master;
splitPoint->mp = mp;
splitPoint->moves = *moves;
splitPoint->cpus = 1;
- splitPoint->pos.copy(p);
+ splitPoint->pos = &p;
splitPoint->parentSstack = sstck;
- for(i = 0; i < ActiveThreads; i++)
- splitPoint->slaves[i] = 0;
-
- // Copy the current position and the search stack to the master thread
- memcpy(splitPoint->sstack[master], sstck, (ply+1)*sizeof(SearchStack));
- Threads[master].splitPoint = splitPoint;
-
- // Make copies of the current position and search stack for each thread
- for(i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint;
- i++)
- if(thread_is_available(i, master)) {
- memcpy(splitPoint->sstack[i], sstck, (ply+1)*sizeof(SearchStack));
- Threads[i].splitPoint = splitPoint;
- splitPoint->slaves[i] = 1;
- splitPoint->cpus++;
- }
+ for (int i = 0; i < ActiveThreads; i++)
+ splitPoint->slaves[i] = 0;
- // Tell the threads that they have work to do. This will make them leave
- // their idle loop.
- for(i = 0; i < ActiveThreads; i++)
- if(i == master || splitPoint->slaves[i]) {
- Threads[i].workIsWaiting = true;
- Threads[i].idle = false;
- Threads[i].stop = false;
- }
+ threads[master].splitPoint = splitPoint;
+ threads[master].activeSplitPoints++;
+ // If we are here it means we are not available
+ assert(threads[master].state != THREAD_AVAILABLE);
+
+ // Allocate available threads setting state to THREAD_BOOKED
+ for (int i = 0; i < ActiveThreads && splitPoint->cpus < MaxThreadsPerSplitPoint; i++)
+ if (thread_is_available(i, master))
+ {
+ threads[i].state = THREAD_BOOKED;
+ threads[i].splitPoint = splitPoint;
+ splitPoint->slaves[i] = 1;
+ splitPoint->cpus++;
+ }
+
+ assert(splitPoint->cpus > 1);
+
+ // We can release the lock because slave threads are already booked and master is not available
lock_release(&MPLock);
- // Everything is set up. The master thread enters the idle loop, from
- // which it will instantly launch a search, because its workIsWaiting
- // slot is 'true'. We send the split point as a second parameter to the
+ // Tell the threads that they have work to do. This will make them leave
+ // their idle loop. But before copy search stack tail for each thread.
+ for (int i = 0; i < ActiveThreads; i++)
+ if (i == master || splitPoint->slaves[i])
+ {
+ memcpy(splitPoint->sstack[i] + ply - 1, sstck + ply - 1, 4 * sizeof(SearchStack));
+
+ assert(i == master || threads[i].state == THREAD_BOOKED);
+
+ threads[i].state = THREAD_WORKISWAITING; // This makes the slave to exit from idle_loop()
+ }
+
+ // Everything is set up. The master thread enters the idle loop, from
+ // which it will instantly launch a search, because its state is
+ // THREAD_WORKISWAITING. We send the split point as a second parameter to the
// idle loop, which means that the main thread will return from the idle
// loop when all threads have finished their work at this split point
- // (i.e. when // splitPoint->cpus == 0).
+ // (i.e. when splitPoint->cpus == 0).
idle_loop(master, splitPoint);
// We have returned from the idle loop, which means that all threads are
- // finished. Update alpha, beta and bestvalue, and return.
+ // finished. Update alpha, beta and bestValue, and return.
lock_grab(&MPLock);
- if(pvNode) *alpha = splitPoint->alpha;
- *beta = splitPoint->beta;
+
+ if (pvNode)
+ *alpha = splitPoint->alpha;
+
*bestValue = splitPoint->bestValue;
- Threads[master].stop = false;
- Threads[master].idle = false;
- Threads[master].activeSplitPoints--;
- Threads[master].splitPoint = splitPoint->parent;
- lock_release(&MPLock);
+ threads[master].activeSplitPoints--;
+ threads[master].splitPoint = splitPoint->parent;
+ lock_release(&MPLock);
return true;
}
// wake_sleeping_threads() wakes up all sleeping threads when it is time
// to start a new search from the root.
- void wake_sleeping_threads() {
- if(ActiveThreads > 1) {
- for(int i = 1; i < ActiveThreads; i++) {
- Threads[i].idle = true;
- Threads[i].workIsWaiting = false;
- }
+ void ThreadsManager::wake_sleeping_threads() {
+
+ assert(AllThreadsShouldSleep);
+ assert(ActiveThreads > 0);
+
+ AllThreadsShouldSleep = false;
+
+ if (ActiveThreads == 1)
+ return;
+
#if !defined(_MSC_VER)
- pthread_mutex_lock(&WaitLock);
- pthread_cond_broadcast(&WaitCond);
- pthread_mutex_unlock(&WaitLock);
+ pthread_mutex_lock(&WaitLock);
+ pthread_cond_broadcast(&WaitCond);
+ pthread_mutex_unlock(&WaitLock);
#else
- for(int i = 1; i < THREAD_MAX; i++)
+ for (int i = 1; i < MAX_THREADS; i++)
SetEvent(SitIdleEvent[i]);
#endif
+
+ }
+
+
+ // put_threads_to_sleep() makes all the threads go to sleep just before
+ // to leave think(), at the end of the search. Threads should have already
+ // finished the job and should be idle.
+
+ void ThreadsManager::put_threads_to_sleep() {
+
+ assert(!AllThreadsShouldSleep);
+
+ // This makes the threads to go to sleep
+ AllThreadsShouldSleep = true;
+ }
+
+ /// The RootMoveList class
+
+ // RootMoveList c'tor
+
+ RootMoveList::RootMoveList(Position& pos, Move searchMoves[]) : count(0) {
+
+ SearchStack ss[PLY_MAX_PLUS_2];
+ MoveStack mlist[MaxRootMoves];
+ StateInfo st;
+ bool includeAllMoves = (searchMoves[0] == MOVE_NONE);
+
+ // Generate all legal moves
+ MoveStack* last = generate_moves(pos, mlist);
+
+ // Add each move to the moves[] array
+ for (MoveStack* cur = mlist; cur != last; cur++)
+ {
+ bool includeMove = includeAllMoves;
+
+ for (int k = 0; !includeMove && searchMoves[k] != MOVE_NONE; k++)
+ includeMove = (searchMoves[k] == cur->move);
+
+ if (!includeMove)
+ continue;
+
+ // Find a quick score for the move
+ init_ss_array(ss);
+ pos.do_move(cur->move, st);
+ moves[count].move = cur->move;
+ moves[count].score = -qsearch(pos, ss, -VALUE_INFINITE, VALUE_INFINITE, Depth(0), 1, 0);
+ moves[count].pv[0] = cur->move;
+ moves[count].pv[1] = MOVE_NONE;
+ pos.undo_move(cur->move);
+ count++;
}
+ sort();
}
- // init_thread() is the function which is called when a new thread is
- // launched. It simply calls the idle_loop() function with the supplied
- // threadID. There are two versions of this function; one for POSIX threads
- // and one for Windows threads.
+ // RootMoveList simple methods definitions
-#if !defined(_MSC_VER)
+ void RootMoveList::set_move_nodes(int moveNum, int64_t nodes) {
- void *init_thread(void *threadID) {
- idle_loop(*(int *)threadID, NULL);
- return NULL;
+ moves[moveNum].nodes = nodes;
+ moves[moveNum].cumulativeNodes += nodes;
}
-#else
+ void RootMoveList::set_beta_counters(int moveNum, int64_t our, int64_t their) {
- DWORD WINAPI init_thread(LPVOID threadID) {
- idle_loop(*(int *)threadID, NULL);
- return NULL;
+ moves[moveNum].ourBeta = our;
+ moves[moveNum].theirBeta = their;
}
-#endif
+ void RootMoveList::set_move_pv(int moveNum, const Move pv[]) {
-}
+ int j;
+
+ for (j = 0; pv[j] != MOVE_NONE; j++)
+ moves[moveNum].pv[j] = pv[j];
+
+ moves[moveNum].pv[j] = MOVE_NONE;
+ }
+
+
+ // RootMoveList::sort() sorts the root move list at the beginning of a new
+ // iteration.
+
+ void RootMoveList::sort() {
+
+ sort_multipv(count - 1); // Sort all items
+ }
+
+
+ // RootMoveList::sort_multipv() sorts the first few moves in the root move
+ // list by their scores and depths. It is used to order the different PVs
+ // correctly in MultiPV mode.
+
+ void RootMoveList::sort_multipv(int n) {
+
+ int i,j;
+
+ for (i = 1; i <= n; i++)
+ {
+ RootMove rm = moves[i];
+ for (j = i; j > 0 && moves[j - 1] < rm; j--)
+ moves[j] = moves[j - 1];
+
+ moves[j] = rm;
+ }
+ }
+
+} // namspace
projects / stockfish / blobdiff